[Ironangel]

Both of my 72 C/10's had factory 3.08 gears, both were factory series 3 carriers, one with the factory Positraction. Factory Positraction I installed a "thick" set of 4.56 gears in the factory unit and race it. My daily driver, the other 72, I went ahead and installed an Eaton series 4 carrier and a set of 3.73 gears. That was/is my tow rig/work horse I beefed up by welding the axle tubes and using a cover girdle. I like the Eaton Posi's because they are rebuildable and period correct. The new Eaton carriers are stronger than the factory carriers GM installed until 81 when the 12-bolt was discontinued. The "Truck 12-bolt" in my opinion, is just as strong as the Ford 9"s as long as they're backed up with cover girdles. Back in the day before every soccer mom drove a 4x4 the two wheel drive Positraction was king!