I bought my kit from the dealer a few years ago. I can't help more than that other than to say that it is NOT a complete kit (GM does not make a complete kit, nor do they have all of the seals available). It does have the input seal, piston seal, the "8" shaped body seal and a couple others, but there are a couple o-rings that are not included. If you only have to do the input seal, then do it, the piston seal and the case seal and you will have enough in the kit (these are the most common seals to leak). If your accumulator is not leaking, leave it alone as the only way to get that o-ring is to buy an accumulator from GM. Deplete the accumulator before you pull the hydroboost from the truck, but just leave it assembled while you do the rest. It is a pretty straight-forward job, no real tricks to it (other than finding a parts guy at GM that can find a kit). The factory service manual has a good description of the procedure.
The only place I ever found the kit was from GM. I could not find any evidence that any p/s or brake manufacturer has ever offered/manufactured one.
