Lou DiMuro umpired at first base in the Chicago-at-Texas game Sunday evening and, crossing a busy street afterward in the Arlington Stadium vicinity, was fatally struck by a car.

Brooklyn native DiMuro ranked with fellow 20th-year man Bill Haller as senior American League umps, and, said Lee MacPhail, AL president: "certainly one of the most popular and personable."

DiMuro, 50, who leaves wife Sue and five children in Tucson, had a meal with fellow umpires of his crew, then went out by himself for a snack, they said. He stepped into the car's path, was knocked into the air and landed on his head. The motorist, David O'Toole, was found blameless.

DiMuro's umpiring crew did not work the Baltimore Orioles-Milwaukee Brewers game last night. Rocky Roe, one of the substitute umpires, said, "It always seems like the misfortunes happen to the really good people." Roe, who reportedly will be joining the crew as DiMuro's replacement on the crew for the rest of the season, said, "I had goosebumps when they had a moment of silence for Lou. It was a great tribute and it showed how close of a family we have here in baseball. You can't replace a guy like Lou DiMuro and I wouldn't attempt to." . . .

Traffic. Just a bit later, in nearby Dallas, police spotted a weaving car, halted it, and the driver had difficulty walking, according to the report on the latest arrest of Bob Hayes, former Cowboy all-pro. Released pending drunk driving charge, Hayes, on parole since February 1980 after serving 10 months of a five-year narcotics sentence, could be reimprisoned if convicted of DWI. But evidently not likely. A Texas official noted that Hayes had no parole officer, had to report to board only once a year, and, "Not many people are put on that. He probably will be put on active supervision because of this, but (parole) probably will not be revoked."

Orioles G.M. Hank Peters, on eminently available shortstop Bucky Dent: "I really don't think the Yankees want to do any business with us. But we have talked and we will continue to talk." About Jim Palmer (3-3), if he consents, for Dent (.165)? . . . New baseball coach at George Washington U.: Jim Goss, former GW infield star, via Churchill High; played Class A at Newark, N.Y., '79, Rocky Mount, N.C., '80; since, coaching Home Plate Club in Clark Griffith League . . . Congress beats major league old-timers to it: annual Dems-GOP game June 16 in Alexandria, nightcap to Dukes-Salem 5:30 game . . . Say it ain't so, ex-Nat Del Unser an old-timer already: 0 for 14, cut by Phillies as Marty Bystrom returns . . . NHL deal: Steve Christoff, Bill Nyrop and second-round pick, Minnesota to Calgary for combative Willi Plett and fourth-rounder.

Billy Kilmer, who quarterbacked almost to 40, plans to settle in now, at 42, working for a bank, in a move a few weeks hence from Fort Lauderdale to Dallas (!). Evidently, the ex-Redskin hit it off with Texas folks during his short stand there as American Football Association commissioner. He resigned that after '81 (summer) season. AFA, on a shoestring with players paid 1 percent of gate, somehow expanded from 12 to 18 teams this season, including Virginia Chargers of Woodbridge-Manassas, but for how long? Defending champion West Virginia Rockets initiated Chargers, 71-7, before 522 customers in a 19,000-seat Charleston stadium (citing "tornado and thunderstorm watch") and the winners' new owner was talking minus $18,000. (Home opener, Saturday night at Manassas Park: Buffalo Gemini 17, Chargers 6.) USFL, though, says Kilmer, is a safe bet--a betting line on its games will ensure its life at least through its two-year ABC-TV contract . . .

All-America: Howard's 1600-meter relay, women, fifth in NCAA track at BYU (3:38.29): Ruperta Charles, Dorothy Wilson, Debra Murphy, Kim Brooks.