I had a Mazda truck do the same thing......and then finally it happened........no warning..........no reverse!!!!! The truck drove fine in forward, but would not reverse. I remember it taking several seconds before the reverse would engage......then "clunk", off I would go. Until one day....I lost reverse. I drove the truck quite a while like this.......parking was always a challange. It even passed our state inspection twice. It's just fine you can fail for a burned out tail lamp, never mind the vehicle doesn't have a reverse gear!!!! Go figure.... However, it sounds like the SL may need a tranny job.
