72 cuda rear end swap

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Old Sep 6, 2010 | 02:59 PM
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cudaracer's Avatar
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72 cuda rear end swap

I have a spare (3.23:1) 8.75" 741 case rear end that I want to replace on my stock 72 cuda, with 318 and 904 transmission.

I assume this is an upgrade. Not sure of what stock ratio I have, but I do know it is NOT a suregrip.

So my main question is, what kit (brrngs, seals, etc.) do I get to install it?
Is there a good source of info as well, book, site, etc?

Thanks.
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Old Sep 6, 2010 | 10:25 PM
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1966sportfury's Avatar
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From: couer d' alene id.
i think it will just drop in pop the axles loose pull the pumpkin then put it back in, maybe the worse will be gaskets
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Old Oct 22, 2010 | 05:02 PM
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Minnesota Guy's Avatar
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72 r/e swap

are you taking out a 8 3/4 rear end already? most came woth 8 3/4's already....if it has 7 1/4 then good swap..just remember that 741 center section is weakest if you ever build for more power.......742 is strongest and next is 489 center section....dont put much into a 741
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Old Oct 22, 2010 | 07:32 PM
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blue 68 gts's Avatar
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From: Lynnhood, Wa
Originally Posted by Minnesota Guy
are you taking out a 8 3/4 rear end already? most came woth 8 3/4's already....if it has 7 1/4 then good swap..just remember that 741 center section is weakest if you ever build for more power.......742 is strongest and next is 489 center section....dont put much into a 741
IMO: the 489 case is better... Has a larger pinion stem then the 742 case. But the 742 case is a clutch type and can be rebuilt unlike a 489.
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Old Oct 25, 2010 | 11:41 AM
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489 case is weaker than 742

the 489 has larger pinion but not as much support as the 742 carrier....742 is stronger at the strip.
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Old Oct 28, 2010 | 06:31 PM
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From: central ,IN
if you already have an 8 3/4 in the car, just take off the axle nuts off each side, pull the axles out, youll need gaskets there, then take the nuts off third member and remove, clean the face good when you remove the center section, then get a gasket there, and also rtv the hell out of it . then replace.
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Old Nov 2, 2010 | 04:59 PM
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Light rtv is fine if combined with the gasket and really only at the bottom...to avoid that pesky drip...
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Old Nov 7, 2010 | 05:59 PM
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From: central ,IN
Minnosota, in 25 years, ive never ounce had a third member gasket and a little rtv seal . Never.It always started by the pesky drip you mentioned, then it got worse. and its embarrising to have drip spots where your car was sitting at a show, or just at the burger joint. So i found that alot of rtv and gasket do the job. It may look like crap around the housing, but its on the inside where you can tsee it and the bitch doesnt leak. . Just an experience thing.
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Old Apr 18, 2011 | 09:07 AM
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cudaracer's Avatar
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So here is the update:

I installed the 741 case, with only RTV, no gasket. Was that a mistake? There was no gasket before, and aside from some lube outside, never any noticable drip.

Also, I noticed the yoke that came with the 741 is bigger and won't match up to the u-joint on the drive shaft. I am having a hard time now taking off the yoke nut, which is torqued down to 240ftlbs.

I also stripped (2 of 5) axle bolts. The ones that slide in from rear of drum case and had to bang them off. Where do I find those?
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Old Apr 18, 2011 | 09:26 AM
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John Van's Avatar
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From: Rensselaer,New York
Originally Posted by cudaracer
So here is the update:

I installed the 741 case, with only RTV, no gasket. Was that a mistake? There was no gasket before, and aside from some lube outside, never any noticable drip.
This is fine,do it all the time!

Originally Posted by cudaracer
Also, I noticed the yoke that came with the 741 is bigger and won't match up to the u-joint on the drive shaft. I am having a hard time now taking off the yoke nut, which is torqued down to 240ftlbs.
They make u-joints that work 7260-7290 Mancini has them:http://chucker54.stores.yahoo.net/spic72to72uj.html

Originally Posted by cudaracer
I also stripped (2 of 5) axle bolts. The ones that slide in from rear of drum case and had to bang them off. Where do I find those?
Any part store should carry them.

Last edited by John Van; Apr 18, 2011 at 09:31 AM.
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