If its the K2500
then you should take into account that you'll need to change the front diff ration also..
OOps sold my "baby" - 96 K-2500 6.5TD - ~047,068mi, Isspro's Boost, Pyro, and Tranny temp; Heath Plate Remote mounted FSD; Amsoil Fluids and Air; Bilsteins, BD Down Pipe-Gutted CAT-& B-D'ized 3.5 Kennedy exhaust; '97 cooling upgrade; CAD upgrade; new IP at 34,700 under warranty; Homemade: Boost fooler, Hi/Lo idle, OPS relay, TCC Lockup ( TFT), Glow extender for AC60's, & "GMC H..'s" 6 position Shift modifier .