THERE is no love more innocent and pure than a man's love for his pickup truck.

It is a rare thing, this love, resembling in many ways the fabled first love which one is said never to forget. Here is mutual devotion of a sort not often witnessed in these selfish times. Here is a love that demands, on the one side, only a high seat and a bauling box, and on the other merely gas and oil (sometimes quite a lot of oil) and an occasional low-gear lug up a long, hard hill to keep the engine breathing free.

This is a touching image, as the most seasoned pragmatist will be forced to admit, and it is one whose charm appears to have spread. You see toy Toyota and dainty Datsun pickups parked in fancy suburbs. You spot LUVs languishing loyally outside fashionable restored townhouses. You spy young executives ensconced inside velvet-lined vans. Macho teen-agers steer four-wheel-drive pickups with burly roll bars. Even Travis McGee -- John D. MacDonald's wry hero -- drives a truck, an electric-blue Rolls Royce convert known as Miss Agnes. Another writer, John Jerome, produced an entire book chronicling his restoration of an ancient Dodge he bought for a few hundred dollars.

The virtues of the truck have penetrated even into the hauls, so to speak, of Congress, where Rep. Andy Ireland of Florida proclaims that to become a member of "exclusive" Redneck Row you "either have to own a pickup truck or have immediate access to one."

Since owning my own truck I have come to understand some of this. At least I understood it at first. While I do not aspire to redneckery -- or to Congress either, for that matter -- I've found that there is something about a truck that seems to elevate its owner, perched up high and stiffly clutching the-big steering wheel, above the common run of humankind. His very altitude provides a form of clairvoyance, because he can see farther down the road than drivers of foolishly road-hugging Camaros, Triumphs and El Dorados.

Yet the trucker must love his vehicle not blindly, but for what it is. Not for comfort or show or machismo, but for its essential Truckness. Or to put it another way: he must love his truck for its deficiencies, of which it will have many.

It is strange, in a way, to witness a truck fad in America. True, we have always been a mobile culture, a culture on wheels, as the cliche goes. But we have never exactly been a hauling culture. From garbage collection to coast-to-coast moves, we have hired out our hauling. And while some Americans have driven for "fun" in the past, and some manufacturers still insist on building so-called "muscle cars" to pander to this nostalgic recollection, since the invention of monotonous interstate highways there are no recreational drivers left except the drunken Texans who inhabit Larry McMurtry's novels. And yet, Chevrolet learned a few years ago that fully half of their trucks are purchased for "non-truck" use, whatever that may be.

Trucks do, however, have charm. Take mine, for instance. It is a 1953 Ford F-100 pickup, issued on Ford's 25th anniversary (a fact commemorated on the horn button), and now in its own 25th year. It is an antique, though it does not look it. It has been restored and painted a kind of deep shimmery green: "metal-flake," I'm told. It has a black Naugahyde seat and Naugahyde door panels, all pleated, rolled and studded with buttons, and I cannot say how many innocent naugas gave their lives that I might sit on this ersatz stuff.

The original steel hauling box was junked and replaced with a custom-made wooden bed varnished to a high golden gloss. This bed is decorated with some fussy Alpine gingerbread which, as people often remark, makes my truck what a truck should never be: cute .

I may as well report here that my truck -- with its massive Thunderbird 390 V-8 and its automatic transmission, its wide tires mounted on "mag" wheels and its fully insulated and carpeted interior -- my truck is bad taste itself. It is a sublimation of a randy teen-age boy's daydreams. It is kitsch on wheels, and that, a first, is why I loved it, the way some people can love only ugly dogs.

I bought this truck from a fellow who had two jobs, went to school at night and was teaching his Vietnamese wife to speak English. He restored the truck in his spare time. Largely because I lack such energy (and as it turned out, such devotion) this truck has changed my life.

It has become that eminently American thing: an educational experience. A consciousness-raiser.

In the past my habit has been to either (a) buy a new car, drive it until it dies, and then take a terrific beating on the trade-in, or (b) buy a used car, drive it till it dies, and then take a terrific beating on junking it. But lately I have read up on old cars as an investment and decided to change all that; buy a nice old truck, keep it in perfect condition and alter the practice of a lifetime. Men reaching 40 are apt to do such things; I felt it healthier to fall in love with a teen-ager's truck than with a teen-ager.

I decided, in any case, to become the sort of person who takes care of his car.

Despite the fact that I have had help, this is more difficult than it seems.

There is an entire subculture of Americans who are involved in the cult of the ancient pickup, people who buy and restore and drive old pickups. Not all are as solemn as Jerome was, who called his restoration of the Dodge "a symbolic recreation of the last rational act on the part of the automobile industry: a private motorcar that would actually do work." For most it is a hobby, an unofficial fraternity.

The restorers are so devoted to the well-being of the great American truck that I felt to hesitation one Sunday morning a week after I bought mine in calling Jerry, from whom I'd bought it, to ask why he thought it was refusing to start. He dropped everything. It took him 30 minutes to perceive that my truck was out of gas. The gauge was broken.

Had I thought clearly, that could have been read as a clue. The fact is, driving 30 minutes on a Sunday morning to help out the sucker who bought my old car is something I would probably not do. Fortunately, not everyone feels that way about trucks.

Near where I live exists a sub-sub-subculture whose members not only are devoted to trucks, not only to pickup trucks, not only to old pickup trucks, not even only to old Ford pickup trucks, but whose tastes are so refined, so finely honed, that they love only old Ford pickup trucks built between the years 1953 and 1956 -- the F-100 series. Like mine.

And that is how I met Paul. Paul can do anything to, with, or for an F-100 truck.

He is a wiry, handsome man of 50 or so, with four F-100s parked in varying states of unsightly dilapidation in his yard, and he is a purist. His first words to me were: "We'll have to get rid of those parking lights. They're not stock. We'll get you some from a junkie." Junkie is his affectionate term for the hard-boiled traders who run junkyards.

Paul's integrity impressed me right away, and I became even more impressed as I got to know him. Here is the sort of fellow he is:

Paul had bought an F-100, and the previous owner had turned it over to him with not one, but two keys. This is not "stock." Generally, the same key fits both ignition and door lock, but the lock had been broken and been replaced. That night he retired late, but stayed awake pondering locks and keys.

At 4 a.m. Paul arose, went outside and removed the lock from the door of his truck, carried it inside to the kitchen table and laid it on a sheet of newspaper. Beside it he placed the two keys. Then, with a paper clip, he dismantled the lock. He spread all the tiny pin-tumblers on the newspaper and spent the next three hours arranging and rearranging them until the ignition key slipped neatly into the door lock and opened it, the way it was "stock."

Then he put the lock together, installed it in the truck, locked up, threw the extra key 50 feet into the weeds, turned off the lights and went comfortably to sleep.

Paul would help me with my truck. I needed help.

At that point I loved my truck with all the romantic and sentimental passion of a young man who has never seen his first love's clotted hairbrush or tripped over her tennis shoes on the stairs. Since I'd owned it, people on the street had been giving me goofy smiles. Old men would approach and say, "I used to have one like that, only it wasn't like that ." Teen-age boys wanted to look under the hood. Older women were mystified by the fuss, but younger women sighed and said, inevitably, "It's so cute ."

A mere glimpse of my truck had turned at least one hardened pedestrian into a starry-eyed hitchhiker: "I just wanted to see it up close," she said. "It's cute ."

People take pictures of it.

The man who delivers lumber likes to sit in it, grinning toothlessly through the old-fashioned flat windshield, gripping the wheel. He cannot read, so he has missed one of the truck's most wondrous features. On the dashboard is a black plastic knob, and from it dangles a cardboard tag reading "PULL ME. " People always do. This is the born. It goes BOOP! and keeps on going BOOP (BOOOOOOOOOoooooooooooooooooo.......) until the knobpuller figures out how to make it stop, which is to push the knob back in (....... ooooop!). This always amuses me. It does not amuse the neighbors.

In the early days, my truck and I were involved in a heavy romance. It has, for instance, running boards. In case you have forgotten or never knew, here is how running boards work:

You park your truck in a glade beside a stream. You turn on the tape deck, you get out, shut the door, pop open a beer. And then you sit on the running board. And drink the beer.

This is such a fine thing that I am eternally surprised not to see more of these running boards, although I think they should change the name. Running, they are unsafe at any speed.

Everybody knows that we Americans buy cars to tell other people who we are. We say we don't, but we do. We say we want cheap, reliable transportation, but what we buy are cars with flash and panache, leather and power, chrome and floss, big engines and whitewall tires and mag wheels and bucket seats and stereo tape decks. Our cars are a form of self-expression.

So was my truck: I admit it. The kitschy Alpine gingerbread, the teen-ager's mag wheels, the absurd automatic transmission and gas-guzzling T-Bird V-8 -- all were part of the fun. Mine is like no other truck in the world. It says, when you see me tooling down the highway: "There goes a guy... with very strange taste in trucks."

There's nothing wrong with bad taste, if it's done tastefully.

Alas, like most loves entered into innocently -- without the skepticism experience teaches -- the truckman's love is subject to disillusionment. It is a disillusionment all the more painful for being at least half-expected. It turns out to be not first love, not young love, but puppy love.

Not that my truck is a dog, far from it. But... well, this story is ultimately about that universal human experience, how one comes to hate what once one loved.

I think it was while helping Paul replace the steering gearbox that I felt the first twinges.

When you violate the classic untiy of the pickup truck, when you breach its quintessential truckness by adding a heavier (and less reliable) engine, for instance, then everything else, like steering and suspension, goes askew. My truck's front end slumps -- rakishly I once thought -- and when I bought it, it steered like a truck.

Paul knew all about this. What was needed, he said, was the steering gearbox from a larger, newer truck, one that would allow the wheel seven turns lock-to-lock rather than six. That adds leverage, or something.

He was enjoying it, poking the greasy dirt from steering gearboxes down at the junkie's place, wrenching off the chosen box and toting the clunky thing to his garage where we cleaned it, removed the old one, crawled on the gritty concrete to drill holes in the frame for the new one... It was my truck; I helped.

I wanted to go sailing. It was Saturday, and Paul worked on trucks on Saturdays. He was having fun. I wanted to go sailing.

It did steer better when we were finished (around sunset), I'll grant that.

But the day broke the spell. I began to see flaws. The affair began to go sour. My truck and I quarreled.

Spitefully, the fan belt broke. Viciously, the radiator sprang a leak. Rebelliously, the door latch shattered.

Hostilities escalated, and I became hard. Neglect set in. What once was kind of insouciant, audacious bad taste and amusing for that, now became in my eyes plain and simple bad taste. My truck, once so beautiful, without changing turned ugly.

And I found myself busy with other things -- new work, a move, new friends, and I began to see that I had bought the truck during a fallow period, a period when I was board. When I had no project to engage me. And when projects turned up, the truck became superfluous. Worse, it became an impediment, a pain in the neck.

And then one night at midnight, as I drove up the newly graveled road to the top of a mountain, the truck went to sleep. It began sliding, backward, backward, down the twisting mountain road, sliding, sliding on the gravel. Then the lights went out. It was a dark night.

It was a case of over the side or into the ditch. I chose the ditch and nearly went over anyway, but with luck, got the truck to slump, amid the sound of gravel grating on the undercarriage, into the ditch.

The truck stayed there two days and two nights, until a neighbor hauled it out and towed it to the Ford dealer, who replaced another fan belt and changed the points and condenser.

Small stuff, and it is still a fine truck. It starts right away when there's gas in it, and on the highway it leaps around Cadillacs and Camaros.

But it is too late now. A woman scorned too long grows hard. My truck tried to kill me on the mountain that night, and the affair is over.

The price is $2,700, and a year ago I would have said it's a bargain.