Ed Asner is crusty and Eileen Brennan is brassy in "Off the Rack," an ABC sitcom getting a trial airing at 9:30 tonight on Channel 7. Like many shows, it's acceptably amusing and once or twice funny, but the prospect of seeing new episodes of it week after week isn't going to make anyone's day. Except maybe Ed Asner's and Eileen Brennan's.

The ghost of Lou Grant will certainly not be banished by Asner's growlly, gruff ("crusty" is the network's word) portrayal of Sam Waltman, a small-time operator in the garment business whose partner's funeral opens the program. Brennan plays the partner's widow, a woman who stayed home for 20 years of marriage and now decides, much to the surviving partner's objection of course, that she will take over his side of the business.

Predictable comic friction erupts predictably in the Dan Guntzelman and Steve Marshall script, but Brennan, returning to series television for the first time since being injured in a traffic accident, makes it seem fresh and zesty. "Sam," she says to the blathering partner, "why is it when I talk to you I feel like I need hip boots?" They're a moderately rollicking sight with cigar and air freshener at about two paces.

Subsidiary characters are feebly contrived and unfunny, but the direction of longtime ace Jay Sandrich is Ginzu sharp. Even when it's on the mark, however, there's not much point to "Off the Rack."