Two years ago, when Grambling first played Southern Methodist in Dallas and lost, 59-27, a student-cowboy on a mustang raced around the field after every SMU touchdown and cheerleaders twisted their bodies into letters Grambling Coach Eddie Robinson could plainly make out from where he stood on the losing bench.

"They were spelling SMU," he said this week. "But I watched that horse more than anything, running round and round and round."

So it was no surprise to Robinson when SMU sent him a letter this week requesting permission to allow its horse to gallop across the turf at Shreveport's Independence Stadium, where Grambling will play SMU Saturday. "That letter wasn't an insult," Robinson said. "I guess SMU just figures they'll be scoring a lot of touchdowns."

"Coach Rob read us the letter," Darryl Nichols, a linebacker, said. "At first, it was kind of hard to understand. We don't believe there'll be that much scoring. And if there is, we don't have a horse to run up and down the field."

Last week, Grambling beat Alcorn State, a Southwestern Athletic Conference rival, in the season opener, 28-0. It was Robinson's 306th career win, 17 short of Paul (Bear) Bryant's record 323, and the first game ever played at Robinson Stadium.

Because Louisiana law forbids the naming of any public facility after a living person, the new 22,000-seat stadium carved out of a red hill in these piney North Louisiana woods, is named after the Robinson family and not after the first and only football coach this school has ever had.

"I never thought the university would make the Robinson name a permanent part of the university," said Robinson, 64, who started here in 1941. "I'd have been happy no matter what they named it. But there's permanence when your name's on a building."

Permanence here is 17 winning Saturdays short of immortality. But because Grambling is a small black college with football teams that have, over the years, played mostly other small black colleges, Robinson is considered by some cynics to be unworthy of claiming the most-victories record from Bryant. The Tide and the G-Men play the same game, it is argued, but a different brand of ball. Thus, the significance of competing against a team like SMU, a national power, is all-important to Robinson and his players.

"When somebody says, 'Eddie Robinson,' people say, 'Who is that?' But say, 'Bear Bryant,' and everybody goes, 'Ah, yes, Bear Bryant,' " Melvin Lewis, a linebacker, said. "That's why this game is everything to us at Grambling. Out of Louisiana, nobody knew who Eddie Robinson was until he got 300 victories. When we beat SMU, it'll give Coach Robinson the recognition he deserves. Grambling'll be in the spotlight at last."

Robert Smith, a defensive end, said, "Maybe if we beat SMU, other big schools'll play us. But I know some won't. They'll be afraid to compete against a school like Grambling, thinking we're a little nothing black school whupping up on the big-timers. It would make it seem like they have everything to lose and we have everything to gain. That alone would scare them off."

Although Grambling has a reputation for producing large numbers of pro players (180 have been invited to pro camps since 1949; nine are currently in the NFL and seven in the USFL), the talent here has dwindled since the major white universities in the state started recruiting black athletes in 1969.

Ruston, home of Louisiana Tech, is only three miles south of Grambling. Northeast Louisiana State, a half-hour away by interstate, and Northwest Louisiana State also crowd the upper part of the state. And there are LSU, Tulane, McNeese, Nichols and Southwestern. Also, Southern, the largest black school in the country, is in south Louisiana.

"I used to get every kid I wanted," Robinson said. "But not anymore. The way it is today is the way it should be, I believe. You can win with the black athlete and you can lose with him, too. An athlete is a human being, but people forget that sometimes. When you touch him at night in the dark, his skin won't tell you what color he is."

Grambling is a Division I-AA school, SMU is I-A; Robinson readily admits he could not compete against teams of SMU's caliber on a week-to-week basis, although, "It's always good to know where you stand. You never know, if things go well, we might whup 'em good. But they might whup us good, too. You've got to be realistic in a situation like this . . . "

In preparation for SMU, Grambling practiced four hours Monday, usually a day of reviewing game films. Three-hour workouts are scheduled for the rest of the week, although talking to the players is enough to assure anyone they're willing to double that drudgery if it would mean extra points against SMU.

"We're practicing harder than they are, I know it," Bennie Thompson, a defensive back, said. "I wish we could play it right now and get it over with. I grew up tough. I'm not intimidated. I'm never scared of anybody. I'm the hardest hitter I know. I know they don't hit as hard as me. They just can't."

The squad usually remains on the field until the sun dips behind a ridge of pines or until thunderheads from Mississippi roll in and split the sky with white flashes.

After practice, Robinson meets in the end zone of the defensive team's practice field, orders everyone to take a knee and talks to his team until he's said enough. Then, long after the team has walked the mile back to the locker room, he remains with "those kids who want to talk about something special, not just football. Us older people, we seem to be afraid to talk to kids about the old values. And how are they gonna know if we don't tell them?"

The other day, Robinson told his team it could beat SMU, and now his players are more than hopeful--they're convinced. "When Coach Robinson read that letter about the horse," Patrick Scott, a wingback, said, "I realized how they didn't take us seriously. They must be blind not to know what kind of defense we have here. We've proven ourselves. I'm not gonna see that horse all night."

Robinson said that after the 1981 game, an SMU assistant coach "apologized to me for what he thought might have been pouring it on when they shouldn't have. I said, 'Hey, you play football and don't worry about all that.' I don't want anybody treating us different than they would anybody else."

Ed Scott, a defensive back, said, "I know we can beat SMU. There's nothing to that. We will beat 'em. A lot of people think if we play it close that's good. Almost is not good enough, though, not at Grambling. If it's an almost game, it'll beat us up emotionally and it'll be hard to get up for the next game. This is the big one, the biggest I or anybody else here will ever play for Coach Robinson."