69 chevy 12 bolt into an 86c10

[JW76]

I have a stock 69 chevy 12 bolt posi rear end out of a pickup. It has 3.73 gears and is 6 lug. What is involved to convert it to five lug and then put it into my 86. Also, the truck has a 355 with 10.5:1 compression, a powermax bracket racing cam, camaro heads, etc. The trans is a turbo 400 with a manual valve body. Are the any modifications that need to be made to make the rear end hold up?

[68c10owner]

Originally Posted by JW76

I have a stock 69 chevy 12 bolt posi rear end out of a pickup. It has 3.73 gears and is 6 lug. What is involved to convert it to five lug and then put it into my 86. Also, the truck has a 355 with 10.5:1 compression, a powermax bracket racing cam, camaro heads, etc. The trans is a turbo 400 with a manual valve body. Are the any modifications that need to be made to make the rear end hold up?

you can buy 5 lug axles for it and get some 5 lug drums. you will need to weld on the leaf spring perches to fit your 86. I think you`ll be fine with it as is for now. My buddy used one with a stock posi and stock axles in a 62 chevy truck and was in the mid 11`s with a 383.

[JW76]

Do you know where you can get the axles from? Do they have to be custom made since the length of the two rear ends is different and the number of splines on the axles are different?

[68c10owner]

Originally Posted by JW76

Do you know where you can get the axles from? Do they have to be custom made since the length of the two rear ends is different and the number of splines on the axles are different?

Almost every vender I see selling 67-72 truck parts offers 5 lug axle conversions. early classics wouls probably be my choice. When you order them, order them for the 1969 rearend. They are just a bit narrower.

[softballnrd27]

Get with moser, currie or any other axle manufacturer and get some made. They can be had for pretty decent prices if you stay away from the beefier stuff. Then you will have to worry about brakes.

[JW76]

What is involved with changing the brakes over? I currently have 15 inch rally rims (the vette style) and I want to make sure I can keep them. Can I take the brakes, backing plates, and drums off my current 5x5 pattern 10 bolt rear end and switch them to the 12 bolt?

[JW76]

Thanks for the tip about early classics. That made my search a heck of a lot easier. They are a lot cheaper than I expected too.

[454HO]

Originally Posted by JW76

I have a stock 69 chevy 12 bolt posi rear end out of a pickup.

Are the any modifications that need to be made to make the rear end hold up?

It depends on what kind of posi is in it. If it's a gov loc, they are supposedly weak. I would say the same is true for an Auburn cone type limited slip. However if you are lucky and it is a Detroit locker or an Eaton limited slip, then it should be plenty stout.

[68c10owner]

Originally Posted by JW76

What is involved with changing the brakes over? I currently have 15 inch rally rims (the vette style) and I want to make sure I can keep them. Can I take the brakes, backing plates, and drums off my current 5x5 pattern 10 bolt rear end and switch them to the 12 bolt?

your brakes will bolt onto the 69 bousing but you`ll have to remove the backing plates and everything. Remember that the 69 rear end is a little narrower than your 86 housing so your wheels may not clear inside. You might be better off finding a 73-up 12 bolt housing and swapping the gears and posi into that one.

Originally Posted by 454HO

It depends on what kind of posi is in it. If it's a gov loc, they are supposedly weak. I would say the same is true for an Auburn cone type limited slip. However if you are lucky and it is a Detroit locker or an Eaton limited slip, then it should be plenty stout.

I`m pretty sure that the 60`s truck posi`s were a clutch type like the eatons. i don`t think the gov lock came out till the 80`s or so but i could be wrong.

[454HO]

Originally Posted by 68c10owner

I`m pretty sure that the 60`s truck posi`s were a clutch type like the eatons. i don`t think the gov lock came out till the 80`s or so but i could be wrong.

The '77 I parted out had a 12-bolt with 3.40 gears and a gov loc.

[JW76]

can my ten bolt rear 5x5 brakes, backing plates, drums, etc. off the 86 just get bolt on the 69 12 bolt 6 lug?

[68c10owner]

Originally Posted by JW76

can my ten bolt rear 5x5 brakes, backing plates, drums, etc. off the 86 just get bolt on the 69 12 bolt 6 lug?

see my last post

[JW76]

after changing the axles to 5 lug of course

[JW76]

thanks for that. i did not see it before.

[JW76]

I have a 12 bolt housing from an 80 Chevrolet with an open diff 2.76. it is 5 lug. I'll get a quote on swapping the posi unit and gears into that one. thanks