output shaft is different in 2wd/4wd .if you still bought it and replaced it ,make sure you replace it with a billet output shaft ,trust me,it was about 4-500 bucks i believe.although you could sell the 1 in it for 2wd to someone,i would say it probly has a 2wd billet shaft in it.good luck.I went through 3-4 output shafts b4 i installed a billet 1,knock on wood no issues with the billet shaft.good luck
mods:2004 sierra ext sb,20s ,big brake kit w,hawk pads,air bagged,2006 6.0 lq4 swap,vortec supercharged10psi, air to water intercooled w/ dual electric fans on it ,snow meth injection kit,60lbers, e-fans ,big radiator swap ,cam 218 /222 548/550 comp .hardened prs .1.85 comp roller rockers ,guideplates ,crane double springs,trans 4l65e built .pacesetter l/ts true duals w/x pipe and magnaflows,14 bolt rearend swap ,3.73s,aroemotive fuel pump system w/elec.fuel controller and bypass regulator a/n fittings, taylor 10.5s interceptor gauge,aem w/b a/f ,autometer boost/vac NELSON 93 OCTANE TUNED .