posi swap

[Jeffs70]

ok I have never done this but I have 2 Rear Ends.

1st one off a 1970 C-10 Leaf Spring Setup with Posi 12bolt.
the 2nd one on 1971 C-10 Coil Spring Setup with out Posi 12bolt.

I want to know how difficult it would be or if its possible to swap the guts inside one another. and If I would need anything special to do the job or maybe even a good Idea to purchase. I searched for a Thread and did not come across one.

I also thought of just welding new perches on each one for the setup and just swapping the rear ends but I noticed the one off the Leaf Spring setup does not have any place for my Pan Hard Bar to bolt to for my Coil Spring setup.

Any Help would be appreciated Thank you

[cdowns]

best way is to weld new perches and panhard bar mount on the posi rear

[Longhorn Man]

do a search on setting gears, you'll see it is just short of an art that not many people know or understand.
If you screw it up, then the gears will be garbage. So if you are able to weld properly, then I agree, it'd be the better choice.

With all that being said, you are doing all this work for a 41 year old posi. Odds are it isn't all that good anymore.

[Jeffs70]

ok Great info to know Thank you. I am glad I didn't just dig into it and cause more problems then its worth. I may just go with welding new perches then if this is an easier way to go.

Thank you again.

[FL71C10]

I think the rear end widths changed from 70 to 71, but I'm not sure.

[Mike C]

This is about the easiest first work you can do in the diff. Buy a carrier installation shim kit and a set of new ring gear bolts. Spend the extra money for the interlocking shims. You will need a dial indicator, a magnetic base, and a caliper.

Set up mag base and dial indicator, measure backlash on ring gear. Write this down! Mark both caps as to left and right and then pull caps. Remove open carrier, remove ring gear. Install ring gear on posi carrier. Use caliper to set up adjustable shim pack equal to the iron shims you pulled out. Put posi carrier back in and torque caps. Check backlash, and if it same as what it was before the swap, you are done. If it is too loose, disassemble again and remove a small shim from side opposite ring gear and install it in shim pack on ring gear side. Reassemble and measure again.

Once backlash is same as it was when you started, double check ring gear bolt torque and bearing cap bolt torque. Put cover back on and add gear oil and limited slip additive.

www.use-enco.com you can get a dial caliper, and mag base, and a dial indicator for less than $50. I have done this re-using the stock shims and not even checking with no problems, but that is your call to make not mine!