At 10:55 last night, Texas oil millionaire J. R. Ewing was gunned down in his penthouse office, his cold blood gushing onto the floor where he lay alone. All America was watching.

It was a mild shock. The scene had been repeated on television at least a dozen times this week in commercials designed to keep us guessing about whodunit. We won't know who killed, or tried to kill, America's newest anti-hero, the star of the hit CBS series "Dallas," until the fall season. But there's room enough for a summer full of speculation. J. R., you see, had many enemies.

Some say there are at least 50,000 people in Dallas who would've loved to pull that trigger. A quick tally from last night's episode shows no fewer than six prime suspects. Every one of them had a motive -- and probably an alibi. So far, no arrests.

At the time of the shooting, J. R. was wallowing in self-congratulation, tickled with his latest dirty deal. Last week he suckered his friends into buying $750 million in Asian oil leases minutes before revolutionaries took over and nationalized the wells.

His daddy, Jock, asked, "J. R., did you know about the nationalization before you sold those wells?"

"No sir. I swear I'd never do anything like that to any of my friends."

Coincidence? Ha!

Let's face it, J. R. was at his nasty best last night. He weaseled lifelong enemy and underdog Cliff Barnes out of half a million dollars, due Barnes' recently deceased father. He charged ex-mistress Christin, also his sister-in-law, with prostitution when he learned of her plans to blackmail him. sHe framed former protege in devilment, Alan Beame, on a phony rape charge. He avoided the wife of a leaseholder who went bankrupt and committed suicide. He committed his wife Sue Ellen, a sweet, drunken and misdirected woman, to a sanitarium on trumped-up charges.

How does he do it? J. R. is rich. Filthy rich. He can buy anything and anybody. And, if the "Dallas" ratings (consistently in the top 10) are any indication, America is saying: "He's our kind of guy."

"It's a shame he got shot. He's my kind of man," a young local "Dallas" fan admitted.

"He deserved it. I would've shot him myself. As a matter of fact, they can consider me a suspect," an otherwise quietly religious woman said.

In McLean, an elderly woman knocked over her glass of hot milk. "My God, they shot J.R." she cried as he lay bleeding, credits rolling over his pain-wracked face.

Whether J. R. lives or dies depends on -- what else? -- money. Larry Hagman, who plays the Stetson-topped Mercedes-driving eldest son of the Ewing clan, is hot property these days. And J. R.'s prognosis may hinge on contract negotiations over the summer with Hagman.

In an interview last week Hagman said: "They figure they'll shoot me on the last show, and if I demand too much money, it's 'the hell with you, you SOB.'"

That's the "Dallas" way.