I didn't know there was a difference.
Borrowed this from Rockauto:
GM GENUINE 07812557
FitsRWD; Extended Cab Pickup; Trans. code NV3500/M50; FRT; 5 speed Manual trans.
orRWD; Extended Cab Pickup; MFI; FRT; 4 speed Automatic trans/M30.
orRWD; Extended Cab Pickup; TBI; FRT; 4 speed Automatic trans/M30.
orRWD; Cab Pickup; MFI; 108.3" Wheelbase; Trans. code NV3500/M50; 5 speed Manual trans.
Or is your NV3500 newer?
GM GENUINE 26051658
FitsFront; RWD; 3 door; Trans. code NV3500/M50; Engine VIN W; Rear Axle; 5 speed Manual trans.
orRear; Front; RWD; 3 door; Engine VIN W; 4 Speed Automatic Trans.
orRear; Front; RWD; 3 Door; Trans. Code NV3500/M50; Engine VIN W; 5 Speed Manual Trans.
They do all use the same u-joint, but you likely won't be able to reuse your front one unless it has already been replaced with one that uses clips instead of injected plastic.
MOOG 534G