The Baltimore Colts announced the resignation of Dick Szymanski as general manager last night. "No successor is to be named at this time," a statement said.

Szymanski served six years as the team's executive vice president and general manager. He was the Colts' second-round draft choice out of Notre Dame in 1955 and played center and linebacker for 13 years before retiring in 1969 and joining the staff as personnel director.

Immediately after the Colts' disastrous 2-14 season last year, team owner Robert Irsay hired Frank Kush as coach to replace the fired Mike McCormack . . .

Tom Cousineau will earn more in his first year with Cleveland than the Browns' entire starting defensive unit did last year, a National Football League Players' Association spokesman said. Cousineau, the former Ohio State linebacker who first passed up the NFL for a more lucrative offer in Canada, will receive a $500,000 annual salary and a $1 million signing bonus, the spokesman said. That would make Cousineau's five-year contract worth about $3.5 million. The Browns' defensive starters last season earned a combined flat salary of $1.02 million, while all defensive players on the roster earned $1.75 million, the NFLPA said. Ed Garvey, executive director of the players' association, said the union is "not trying to make any point by this" . . .

Los Angeles Rams wide receiver Drew Hill was given a one-year suspended sentence and three years probation for contributing to the delinquency of a minor in a case involving a 16-year-old girl. Charges of attempted unlawful intercourse and assault and battery were dropped at the sentencing proceedings in Fullerton, Calif. North Orange County Municipal Judge David Bach also ordered the player to perform 400 hours community service before Aug. 5. Hill, 25, originally was accused of assaulting the Buena Park, Calif., girl at a party at his house Dec. 20 after the Rams' last 1981 game. Hill pleaded guilty in February to the misdemeanor count of contributing to the girl's delinquency. He could have been sentenced to up to one year in prison or fined $2,500 . . .

The Washington Redskins announced signing five rookie free agents: quarterback Chris Garrity (6-1, 185) from William and Mary, defensive back Greg Williams (5-11, 190) from Mississippi State, wide receiver Kirk Wilson (5-11, 188) from Indiana State and linebacker John Andreoli (6-3, 236) and punter Tim Barry (6-2, 205), both from Holy Cross . . .

Joe Montana, quarterback of the Super Bowl champion San Francisco 49ers, says he doesn't agree with some of the issues that might produce the threatened walkout by members of the NFL Players Association. "A percentage (for the players) of the gross is kind of ridiculous," said Montana. "I think 95 percent of the players are willing to say they'd strike, but I don't think 95 percent will say they agree with the issues.