rear diff

[tce_lonestar]

I own a 1986 C-10, which I have planned to make a 6.0 bored to 408 swap, and a fuel inyection conversion, a 4L80 tranny and a radix supercharger, I think that the numbers should be close to 580 HP at the rear wheels and the same amount of torque, the only thing I don`t know is: what diff can handle the power without having to be rapaired every 2 weeks. I`ll appreciate your help guys.

[RedHeartbeat]

With that much TQ/HP you're going to be breaking everything in that truck from bumper to bumper. Correctly built, the 10bolt will handle it but I think I'd go ahead and get a 9" for that much power.

[badseed91]

I would blow up the exsisting diff first, video tape and take pics. Not at the track of course cause that will take forever to clean up especailly @1/2 track pissing everybody off. then find the cheapest diff that is bigger than the last one you broke and try to break it. when you find one that holds up build that diff which will probaly be a 9" or 12 bolt or better. You want to make sure you set the diff up properly in the truck especailly pinion angle. One of the main things you want to look for in an diff is the ring gear diameter. 99% of the time the bigger the ring gear the stronger the diff is. There are billions of parts out there for the 9" which makes it the most popular swap. Its like the small block chevy of the differentials. However a well built 10 bolt safely will handle a max 650hp in a car so probably 600hp or less in a heavy truck. I have an 85' c-10 and im going with a 14 bolt 9.5" from an 05' silverado 1/2 ton mainly because i got it dirt cheap and cause if i blow up the diff in my daily driver in the mean time i will have one to replace it.

[gearheadnate]

I thought they used a 12 bolt untill '88. If not you can get one that will bolt right in. It would be a truck 12 bolt which the pinion isn't as big as a cars but the are still plenty strong. A freind of mine is pushing close to 600hp on a truck 12 bolt with a 35 spline axle upgrade, his is a '78. If you don't trust a truck 12 bolt, get one out of a car. The car 12 bolt are getting harder to find in salvage yards but the truck 12 bolts are a dime a dozen. I don't like the 9" bacause it doesn't use c-clips, the axles are a pain to get in and out.