As far as nodified clutch packs, I looked and didn't find any service information on that, but when looking at parts info it depends which tranny you have. If it is a 722.624 or 722.636 there are modified pieces to the assemblies after a certain chassis number. If it is a 722.670 trans there show no modifications. The 722.670 trans has the latest pieces inside from the outset. Send me your chassis number and I'll look up the pieces.