[BarryGMC]

I just saw your pic on the 67-72 site. Cool truck. Post a pic of the spid if it's still on the glovebox door. Second look at the rear end cover there may be a tag still on it, if it's there get the numbers off it. I am guessing 4.10. Since you did the trans work already I would suggest 3.54 gears in the rear. All of my gmc 3/4 tons get this ratio, and I find it a good compromise. Barry