Need 12 Bolt Info
 

I recently bought a '66 C10 and joined this Forum. It needed a rear end and I found a 12 bolt truck rear with the 6 lug axles. Since I want to convert it to the 5 on 5 pattern to match the disc brake front I installed, I found a 12 bolt truck rear of unknown vintage, with the 5 on 5, and the axles have the 30 splines and appear to be correct, and they go right into my housing, but they are apx 1/2 inch longer than the 6 lug original axles. I wonder what axles will fit as the originals did? And does anyone have any for sale? Thanks for any help. This is a great Forum.

Maybe the way to go is to redrill the 6 lug axles to 5 on 5, if I can find a machine shop that can do it. I think the old-school shops where we could get small jobs done are fast becoming extinct.

Re: Need 12 Bolt Info
 

I think the axles up through '69 were considered short and then '70 and up were ~1" wider. I'm sure someone will chime in who knows for sure.

Re: Need 12 Bolt Info
 

Yeah hes right in the late 60s early 70s they made the rear end wider,Yeah you could have your 6 lug axles changed to 5 lug or even the 5 lug ones shortened to fit.

Re: Need 12 Bolt Info
 

I'm pretty certain that when they changed the bolt pattern to 5x5 in '71, the rear end width increased 1.5" total, and that width was unchanged all the way to 1987.

Options:
1): You can buy 5x5 "conversion" axles for your original rear end.

2): You can have your 6 lug axles redrilled for 5x5, but it really weakens the axle flange. The end will look like swiss cheese.

3): You can't shorten the stock 5x5 axle to work in your '66. The 12-bolt axles are retained with c-clips, and if you shorten them to fit, you have to machine off the section that retains the c-clip. Sure, you could probably have the stock axles cut, resplined, and machined for the c-clip, but after all that was done, you'd be better off buying the conversion axles.

You will need the entire rear brake assembly from a '71 to '87 half ton. I would suggest finding a heavy duty set-up with the wider brake shoes.