does the 3500 have the same rear end? on 2001 GMC Sierra 2500 HD

I found a 2005 GMC 3500 dully rear end I want to know if it will go under my 2500 HD 4x4 will the rear end gears be the same

Asked by for the 2001 GMC Sierra 2500 HD
The differential will bolt up under your 2500. The tag on the differential should tell you what the gear ratio is. If the tag is missing you can either count the ring gears or count how many times you turn the pinion to get 1 revolution of an axle shaft.