When shopping for a replacement booster, I find that all the auto parts stores' databases reference a booster with a different piston than tat of the original booster. The hole in the top of the piston is about 3/32 too small to slip over the corresponding peg on the brake pedal. I can swap with the piston on the original booster, but then it comes about the same distance from bottoming-out in the sleeve on the booster (if the retaining clip is attached).
I can't figure out why that is; I bought the car new off the lot, so I know the old booster is the factory original. All I can figure is that some engineer decided to substitute another booster in mid-manufacturing, but if so, why don't the stores' databases reflect alternate boosters? I wondered if maybe a 2001 booster was used; it has a different part number, but I can't find a store that stocks it, so I can't compare. I've also tried looking at a 1999 model, and the boosters of equivalent Olds/Buick models, but either get the same booster, or the "we don't stock it -- but can order it for you" message -- regardless of what chain I go to.
Any ideas would be appreciated.