Rearend Compatability
Thread Starter
Racer
Joined: Feb 2007
Posts: 389
Likes: 7
From: Cliffwood Beach NJ
Rearend Compatability
I am looking to swap out my rear end on the 68 to 4:11s. Just have a couple of questions. Are all 63 to 79 rearend compatable? If it has HD side yokes, will there need to be a corresponding upgrade to the halfshafts?
Thanks
Thanks
Abby Normal
Joined: Dec 2001
Posts: 53,452
Likes: 92
From: Press "2" for English
i am by no means an authority on the iron 36's but as i understand it they are all interchangable physically, as far as in the framerails. the only issue, as you mentioned, should be the half shaft yokes. i don't remember the exact numbers but i think the HD yokes were 1/2" wider than the standard yokes.
if you're going to 4.11 though, it probably wouldn't be a bad idea to upgrade the half shafts and spindle yokes too.
if you're going to 4.11 though, it probably wouldn't be a bad idea to upgrade the half shafts and spindle yokes too.
Team Owner
Joined: Oct 2004
Posts: 23,831
Likes: 10
From: Springfield MO
St. Jude Donor '07
I think (though I'm by no means positive) that the u-joints are the same, the HD yokes are just heavier and use caps rather than the strap bolts.
Tech Contributor
Joined: Aug 1999
Posts: 15,175
Likes: 3,987
From: Connecticut, USA
Any 63-79 iron unit will fit your car. There are some differences internally and I would look for a 71-79. Now if you're planning on just bolting in a used 411 diff be prepared for possible problems. Check it out good before installing, most used diff's I see need attention and 411 units were usually pounded on. If you go with an early one,63-68 check the posi case very carefully.
Be aware the posi cases are different between a 3series gear(273-370) and the 4 series (411 456 488)
The HD yokes just have the caps that's all.The yoke are the same other then the holes to secure the joint. Your 1/2 shafts are fine to use, maybe upgrade to a Spicer solid joint.
If you need more info PM me and I'll link you to everything you need to know about a vette diff.
Be aware the posi cases are different between a 3series gear(273-370) and the 4 series (411 456 488)
The HD yokes just have the caps that's all.The yoke are the same other then the holes to secure the joint. Your 1/2 shafts are fine to use, maybe upgrade to a Spicer solid joint.
If you need more info PM me and I'll link you to everything you need to know about a vette diff.
Team Owner
Joined: Aug 1999
Posts: 42,487
Likes: 47
SPARTAN
CI 3-4-5-6-8-9-10 Vet
CI-9 AutoX Winner
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St. Jude '03-'04-'05-'06-'07-'08-'09-'10-'11
Any 63-79 iron unit will fit your car. There are some differences internally and I would look for a 71-79. Now if you're planning on just bolting in a used 411 diff be prepared for possible problems. Check it out good before installing, most used diff's I see need attention and 411 units were usually pounded on. If you go with an early one,63-68 check the posi case very carefully.
Be aware the posi cases are different between a 3series gear(273-370) and the 4 series (411 456 488)
The HD yokes just have the caps that's all.The yoke are the same other then the holes to secure the joint. Your 1/2 shafts are fine to use, maybe upgrade to a Spicer solid joint.
If you need more info PM me and I'll link you to everything you need to know about a vette diff.
Be aware the posi cases are different between a 3series gear(273-370) and the 4 series (411 456 488)
The HD yokes just have the caps that's all.The yoke are the same other then the holes to secure the joint. Your 1/2 shafts are fine to use, maybe upgrade to a Spicer solid joint.
If you need more info PM me and I'll link you to everything you need to know about a vette diff.
Good information right there. Check the posi case carefully, and you may even want to update it if you plan on pounding on it. As Gary said, you'll need a different posi case for the 411 if you're running a smaller gear in it currently. The side-to-side position of the face that the ring gear mounts to is different between the 3s & 4s.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
One thing not mentioned. The pinion yoke went to a larger size in 1969 or 70, can't remember which year but the u-joint is wider on the newer pinion yokes than the older pinion yokes.
Tech Contributor
Joined: Aug 1999
Posts: 15,175
Likes: 3,987
From: Connecticut, USA
Very good point. The early units will have the small yoke then for a couple of years they were split between the small and large and then finally the large. Also the yoke OD is very often overlooked in a rebuild as the speedy sleeves run about $30 and a good used yoke about $75-$100.
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Tech Contributor
Joined: Aug 1999
Posts: 15,175
Likes: 3,987
From: Connecticut, USA
You can swap the yokes the spline is the same. You want to follow the correct preoad procedure if you do and use #271 loctite on the threads and # 2 on the splines. Might as well replace the pinion seal.
