Full rear end swap?

[BigRandy]

I want to do a full rear end swap in my 74 C-10. Can someone tell me what rear ends would be a direct bolt up match? I'm guessing 73-87 but would that be the limit without doing surgery?

Thanks!

[andrewmp6]

Yes 73-87 half ton 2wd are what you need to look at,Any bigger truck/4x4 will have the wrong lug pattern.And any other years will take welding to fit.

[BigRandy]

Originally Posted by andrewmp6

Yes 73-87 half ton 2wd are what you need to look at,Any bigger truck/4x4 will have the wrong lug pattern.And any other years will take welding to fit.

That's what I was sort of expecting. Thanks for the reply and for clearing that up. It's a 2WD and I'm going to be hitting the salvage yards soon.

[Warrens69GMC]

Search here, save some gas and time.....

www.car-part.com

[andrewmp6]

The 4x4 ones are different lug pattern,But i think if your axle and it are the same you could swap axle shafts and drums.But i have to ask whats wrong with the one you have now ?

[BigRandy]

Originally Posted by andrewmp6

The 4x4 ones are different lug pattern,But i think if your axle and it are the same you could swap axle shafts and drums.But i have to ask whats wrong with the one you have now ?

Nothing wrong with it at all but my comfort speed on the highway is 70-75 and there's a very thirsty 454 turning those 3.73's.

I've had the truck about a month and haven't pulled the cover off but I don't think the carrier will support a 3.42 or 3.08. I could be wrong about that but since I have no experience setting up rear end gears figured it would be easier in the end to swap it with a complete unit - as long as it's a direct fit.

[andrewmp6]

Why not pay a shop to re gear it for you ?A used rear axle could be in better shape or pretty much scrap lol.Which trans do you have ?

[BigRandy]

Originally Posted by andrewmp6

Why not pay a shop to re gear it for you ?A used rear axle could be in better shape or pretty much scrap lol.Which trans do you have ?

TH-400

I talked to a shop yesterday and was told it could run 4 grand. I don't think they wanted the job.

[BigRandy]

Originally Posted by Warrens69GMC

Search here, save some gas and time.....

www.car-part.com

Great link. I didn't know it existed. I'll be up all night

Thanks!

[Rickysnickers]

Originally Posted by BigRandy

TH-400

I talked to a shop yesterday and was told it could run 4 grand. I don't think they wanted the job.

$4k to install new gears in the rear axle??? Run far away from that shop!

[Warrens69GMC]

Originally Posted by BigRandy

Great link. I didn't know it existed. I'll be up all night

Thanks!

[andrewmp6]

4k what are they smoking lol.Talk to other places it should be no where that high.

[BigRandy]

I don't know what they were on either but I 'bout stroked out when I heard the price. Seemed clear enough to me that they either have enough work where they can pick and chose or they just don't want to do rear end work. Maybe they don't have anyone who knows how. Whatever the reason I sure won't be going back. I'd rather be turned away than get low balled or burned by some amateur.

I'm not in a rush to swap. Got a ton of body work and other things to fix right now, but the rear end is on my radar and I wanted to get an idea now so I would know what to look for if I found one locally.

Anyone buy from the list of salvage dealers in the link Warren added? Any "gotchas" to watch for? The nearest goldmine in there looks to be about 168 miles from me, and if the parts are as good as some of them look, it might be best to take a trip and load up with the major body parts I need and grab a rear end while I'm at it.

[Warrens69GMC]

CALL to make sure they still have the parts you are after.
With the axle, ask if you can see the truck its coming out of and I would remove the differential cover and look at the gears to see if everything is ok BEFORE you leave.

[BigRandy]

Originally Posted by Warrens69GMC

CALL to make sure they still have the parts you are after.
With the axle, ask if you can see the truck its coming out of and I would remove the differential cover and look at the gears to see if everything is ok BEFORE you leave.

Yes, thanks. I would certainly want to look inside before handing over the cash. Good tip!

[Pontiac1976]

You should have 12 bolt from factory 73-81 after there 10 bolts If I remember right.

[Warrens69GMC]

10 bolts were in them since 1973. My 1978 has a 8.6 in it factory

[N2TRUX]

Originally Posted by Warrens69GMC

10 bolts were in them since 1973. My 1978 has a 8.6 in it factory

Not true. I'm not certain on the year break, but I think it was 77. Earlier trucks had 12 bolts in C10s.

Now we can start the controversy over which is stronger, truck or car 12 bolt. Dont forget 12 bolt vs 10 bolt.

BTW- They shop that quoted 4k probably wasn't too far off average. To do a complete gear change including gears and a locker its commonly priced around 3k or higher.

[D13]

my 77 has a 12 bolt, my 80's trucks are all 10 bolt.
gear set + posi + good install kit will run ~800 just in parts. Do you need axles? Brake pads, drums, parking brake parts (there's a difference in park brake cables somewhere in there..)? Looking for a disc conversion? And since the drive shaft is out, it's a good time to do U joints, and a center carrier if 2 piece, and that rear trans seal and trans mount.

If you do put in a 10 bolt you will need a conversion U joint (not expensive).
While 4k seems a little silly, certainly $2000-2500 to have someone build one is not out of line.
The posi is the expensive part, but good bearings add up.
Also think about brakes, if it's a factory big block you may have the large brakes, and a lower geared axle may not. You would have to switch backing plates or live with lighter brakes, which really wants a different master cylinder.
Before you do this, sit down and calculate how much gas you'd be saving. Unless you get the axle dirt cheap it usually cost more then you would save.

[Bloodhound]

12 bolts through '81. 10 bolts started in '82.