The Stovebolt Site Forums The Shop Area Engine Shop Yet another rearend question........

Ok guys so how come The only option for a rearend gear besides the 3.90 is the 3.38?(1960 C10) If it's a GM 10 bolt assuming it's a 8.20 or 8.50in dia. gear why can't I use other gears listed for that size? I was looking with my buddy who works at NAPA in there performance parts and there were all kinds of gear ratios (even the 3.90 but no 3.38) I was looking at a Richmond 3.08 gear but again before I make any decisions I know there has to be a reason why there's a problem with this or I'd hear all you guys saying you can easily put gears in the rear and not have to special order the 3.38. -Thanks Danny

There are a number of factors besides ring gear size. How many, size, and spacing of the holes that mount the ring gear to the carrier. Can you find a pinion bearing that has the correct ID for the pinion and a matching race with the correct OD to fit the housing. Is the center of the ring gear to the rear face of the pinion close enough to where it can be shimmed to the number etched on the back of the pinion (or found in an assembly manual). If there are gears that meet these conditions then they will fit. I have read where some have said they change out the whole third member which if possible would be alot easier and probably cheaper.

I not 100% sure but I think the orignal rear end assemblys in the 67-72 half ton trucks were 12 bolts. The gears are different between the truck and the car 12 bolt. There ane many ratios avaiable for these rear ends.

Sean

The G.M. rear end up through 62 was a whole different animal than the latter models. 3.90 is the highest ratio they used except for a few 3.38 in 59 which are very rare. The after market produces a 3.38 gear set. They were unavailable for about 2 years but are readily available now. When we couldn,t get one for my partners 60 panel we installed the complete rear end from a 70 model with 3.08 gears. We had to buy a bracket kit & special panhard bar. It worked good but I would rather change the gears.

Woops I miss read what year your truck is, sorry that post of mine doesn't really apply to a 60 C10 at all. Sorry bout that.

Sean

The ring gear in a '60 would be a 9.375", it's also a 12 bolt ring gear. Only the cover is 10 bolt. According to the manuals, they did make them with 3.38, 3.90, and 4.10 gears. Later 12 bolt gears do not swap.

Thanks Bill, I think that's the key info I was looking for.