I have found a company called Art Housers Rear Ends that sells 3.90 and 4.11 gear sets for the 3/4 and 1 tons. Has anyone out there done business with them or heard anything about them? Also, let me ask you guys this. Will the ring and pinion from the 66-72 heavier duty rear ends fit the earlier 47-53 3/4 and 1 ton? And my last question, thanks for your patience. My rear end has a large bolt on the side that goes into the case right in line with the pinion. I assume that it adjusts the pinion somehow. Anyone know what it does? Thanks a lot! I have picked up so much from this site already. You guys are great.