Rear end swap

is ur truck 4x4? if so then u have to make sure they are the same gear ratio if its just 2wheel then u should have no problem

Since the C2500 is a two wheel drive, the only issues you may run into are: Rear wheel offset, park brake cables, leaf Ubolt clamps and rear universal joint. Just measure everything up carefully prior to swapping. If the diff ratio is different, you'll need to replace the DRAC module (by the ECM) to correct the speedo.

the 2500 hd and the 3500 both use 14 bolt corp axles some 2500hd trucks use a semi floater if the if they both have the full floater axle they are the same rear end and really is a waste of time to swap unless one has a lower gear the pic is a full floater if your truck has one of these they are the toughest rear end gm ever made and is no point in changing it. if it dosent have the stick out like the pic follow Lyndon advice

I put a 14 bolt rear end under my 94 chevy k1500 4x4 it has 4.10 gears in the rear end what gears do I need in the front end to run it in 4x4 or do I even need to change out the 8.25 gears

Not all c2500 and c3500 used the full floater. It depends on the year, some c3500 trucks used the semi-floating rear axle, it's confusing at best but the pic from Eric is the key to identifying a full floating rear. Some of the interchange systems even get it wrong so know what you have and what you're looking at. In the C2500HD and C3500 world you always see the 8 bolt wheels (4x2 and 4x4) but if there's no axle end cap with bolts under a center cap then take a look at the rear diff cover and count. If there's no axle end cap and it has 10 bolt rear cover then it's semi-floating regardless of 3/4 or tonner.