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Old 02-02-2001, 06:17 PM   #1
Fast68Chevy
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Post Quick rear axle swap question..


Will the '76 C-20 10.5" rear axle bolt up under the 81 C-20, which has a 9.5" right now?
Driveshaft yoke mods? Parking brake cable mods ??
I'd love to have the 3.73 locker under the '81...
Thanks for anything...!

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'68 C-10, '81 C-20, '79 CM-400 '72 Blazer,
'79 Caprice,'77 Electra,
'76 C-20, '78 C-10, '83 Caprice
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Old 02-02-2001, 08:36 PM   #2
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From what I can remember, you shouldn't have to modify it to fit, ie p-brake, yoke. I think they changed the p-brake routing in '84, but you can check by looking on the drivers framerail to see if both cables run down that side. U-joints should be the same.

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Old 02-02-2001, 10:54 PM   #3
Fast68Chevy
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I hope it goes in, with no mods,
worried about axle tube diameter though, the tubes on the 10.5" are pretty darn big, hmmm

I dont think I'm gonna be able to get out of here as quick as I think I can. So, I guess I have time to do this swap, beforehand..

Thanks, Chris!
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Old 02-12-2001, 09:19 AM   #4
Mike - 76 k20
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Your stock rear axle is the 14bolt SemiFloat. It is a very stout axle.
You want to put in a 14bolt FullFloater. It is practically indestructible. A lot of the 4x4 crowd (including myself) use these because they can withstand anything. I swapped mine in after I broke my 12-bolt (8.875" SF) axle.
Anyway, YES it is very swappable. The spring perch location will be the same. If the donor truck had been a c30, it would NOT fit, but because it came from a 3/4 ton it will fit perfectly.
I'm not sure what size yoke your SF axle has. It's either a 1330 or a 1350. The FF axle you want has a 1350. If it turns out your SF has the 1330 and you do not want to buy a new driveshaft (about $300) you can buy a conversion ujoint from NAPA that has 1330 caps on one side and 1350 caps on the other. It's about $20 I think.
Not sure about parking brake. I took off the drums on my 14bolt FF and put on discs.

You do know the FF axle has bolt-retained axles, right? So, in the center of your wheels, you will see 8 bolt heads instead of a semifloat axle flange. If you use hub caps or whatever, it will cover them up. I like the way it looks on my 4x4 (uncovered), but the 2wd crowd usually doesn't like the look.
-- Mike (call me Mr. Axle
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Old 02-12-2001, 09:22 AM   #5
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Oh yeah, in regards to chris who mentioned axle tube diameter. Yes the axle tubes are larger in diameter and you will need to get the ubolts off the donor truck. You also want the spring anchor plate (that the ends of the ubolts go through.) That's all, no biggie. If the ubolts and not savable, you can buy new ones from just about every parts catalog. They are like $40 for a set of two. I recommend just getting them off the donor truck.
It's a really easy swap. Just have some friends, that axle weighs about 600 lbs.
-- Mike
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Old 02-12-2001, 12:21 PM   #6
Fast68Chevy
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They both seem to be full floaters, they both have hubs, but the pumpkin under the '81 is smaller.(9.5")
I already cut the U bolts that were holding the 10.5" to the 76 leaves, so I will have to get new U bolts.
Im just worried about the U joints.
How do you know about these U joint part numbers? Hows that work ?
That 10.5" is pretty damn heavy, im gonna wrap the log chain around it, and drag it up the lot, here in a bit, then drag the rear half frame of the truck too.

Thank you for the info!

------------------
'68 C-10, '81 C-20, '79 CM-400 '72 Blazer,
'79 Caprice,'77 Electra,
'76 C-20, '78 C-10, '83 Caprice
"How do you want to crash today?"
-- New Microsoft Slogan for Windows
Lincoln, IL, 30 Mi N of Springfield
r72k5@hotmail.com


[This message has been edited by Fast68Chevy (edited 02-12-2001).]
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