Diff/rear end upgrade or opinions. Wheel implications.

[t76turbo]

I just bought my first C-10. A '70 swb 2wd C-10 Custom although I need to confirm everything on the SPID when it gets here. It is taking the slow boat and should be here start of next week.

I was going to go ahead and order wheels shortly after I get it and confirm what I am dealing with. From what I can tell from the pics, it has a 10 bolt. I have heard a 70 should have a 12 but I count 5 bolts below the axle line so I have to assume there are 5 above it.

The truck does have a newer Vortec headed sbc so I wouldnt doubt it had a rear end swap at some point also.

When I get the truck, what should I check to confirm if it is the narrow rear or the wider? Or are all 10 bolts the same width? I would need to know to adjust the backspace of the wheel I order.


Along the same lines, would it be worth hunting down a 12 bolt and rebuilding it including limited slip etc and just swap it instead of dealing with the 10 bolt? I have read stories of guys running 9 second quarter miles with 10 bolts in a Camaro.

[Longhorn Man]

a 10 bolt would be a full up custom install since these trucks came with 12 bolts (and a very small handfull of danas) from the factory.

[t76turbo]

Maybe I am mistaken. Here is the only pic I have of the diff.

[cdowns]

i think you'd b better off waiting to get the truck inspect it live with it for awhile and formulate a long term plan based on what you find is actually in your possesion

[LONGHAIR]

That looks like a "car" 10 bolt, have you measured the bolt pattern of the lugs?

[68Stepbed]

that looks like a 10 bolt. I would wait until you get it and determine what you really have. If it's an 8.5" 10 bolt, it's worth working with. You may be about as well to find an original 12 bolt and build it.

[Bishops Trucks]

I posted some good truck 12 bolt rear goodies for sale on here. I have a friend that had a '69 Camaros with a built 10 bolt in it. Very strong rear and handled the 480 ponies he had just fine.

[t76turbo]

Thanks for all the info. I will just confirm everything in person and go from there. With all the variations, I guess it isn't just as simple as 10 v 12.

Guess I am trying to get too much of a head start on everything!

[Bishops Trucks]

Take it slow, the decisions will come.

[t76turbo]

Ok. I got the truck a couple days ago. I will be putting it up on a friends lift this weekend hopefully to just go through stuff and try and confirm what I am starting with.

What do I measure to help pin down exactly what rear end I am dealing with? Or is there a stamping I can look for? It is clearly a 10 bolt. But beyond that I guess I would need to know if it is the same width as the narrower version or wider these trucks typically come with to know offset of wheels.

There is just a little moisture around the bottom of the cover so I am going to pull the cover off it and reseal/refill.

[68Stepbed]

http://www.ringpinion.com/DiffList.a...=Diff&TypeID=5

http://www.ringpinion.com/DiffDetail...26DiffID%3d210

According to this info, it looks to be an 8.2" BOP rearend.

[t76turbo]

Originally Posted by 68Stepbed

http://www.ringpinion.com/DiffList.a...=Diff&TypeID=5

http://www.ringpinion.com/DiffDetail...26DiffID%3d210

According to this info, it looks to be an 8.2" BOP rearend.

Per the pictures, you are correct. I guess I may have a Frankenstein on my hands. A Buick, Oldsmobile & Pontiac rear end along with my unknown year SBC with the vortec heads with bolts down the center of the valve covers.


Man I wish i could ask the PO what he was thinking.

[t76turbo]

So I got the truck and have been dealing with other stuff. It is time to get back to identifying what I am dealing with.

Here are some pictures. I need to clean the cover off and maybe wipe it down with wd-40 to get a better picture of the shape of the diff cover. But this is better than nothing. It definitely is the shape of the BOP cover linked to above. Except maybe the little nose isnt as pronounced.

But here is what I know so far. Please tell me what else I can do or info I can obtain to clear it up.

-10 bolt cover obviously.
-The axles are 5x5 bolt pattern.
-The brake shoes appear to match the measurements of a 1978 G20 van. The shoes were 11x2.75 which is larger than the factory application 10bolt and the wheel cylinders were larger as well. But the diff cover doesnt match.

[ItsRandy]

You can put in a 9" Ford with a Detroit locker, 35 spline axels, Wilwood brakes, your choice of gear ratio and what ever width you like for close to the same money you would spend to build a 10 or 12 bolt (and never break it).

[t76turbo]

Originally Posted by ItsRandy

You can put in a 9" Ford with a Detroit locker, 35 spline axels, Wilwood brakes, your choice of gear ratio and what ever width you like for close to the same money you would spend to build a 10 or 12 bolt (and never break it).

I know. Replacing what I have is a thought. 9inch came to mind. But I doubt I will go the big power route on this truck like I have done for the last few vehicles I have built.

My biggest concern now is to just figure out EXACTLY what I have now.

[68Stepbed]

OK, It's definetly the 8.2" BOP. With it having the 5x5" lug pattern, it could be from a larger car from the mid to late 70's. They had the 5x5" bp. If you don't plan to throw alot of hp to it, I would either stick with what you have or try to find a stock rearend.