I have an 89 Sierra reg cab. The bench seat does not fold forward. If I recall correctly from my 88 reg cab in the 90's, there is no release you just have to wiggle it to get it to fold. I have tried a lot of wiggling an the Sierra seat will not fold. Does these commonly break or is it something that needs to be cleaned and lubed occasionally? I just took the seat out to dye the carpet, I have not looked but assume the release is only on the driver's side.