I have same, but a 90 Jimmy, stock axle ratio according to build sticker is 3.42. According to specs some had 3.90 or 3.91, and there were a lot of 3.23. I have the HD Trans with code MD8 with MX0 overdrive, which means a Auto 4 spd, HMD, 470E Super Duty. Sent tranny & transfer case to reputable shop for upgrade to kevlar bands etc. and non-lockup, which required a different torque converter. Rebuild cost for trans & transfer case about $2500. I am doing an engine swap to a 383 strocker with al heads, roller cam, and Holley Sniper system, expect close to 500 hp. Also, lifted 2.5" which required changing rear drive shaft, & steering pitman arm replacement, plus a few other mods.