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sure grip question

Monkeymaster

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Hello,
I have a 1969 charger 8 3/4, 489 case, rear end, with open differential and 3.91 gears.
I will be putting this under a 66 charger, with a 383 automatic.
I have seen some 481 cases on Craigs list, with sure grips, at some decent prices.
I WILL stay with the 489 and its thicker shaft, so.....
Will a sure grip from a 481 case, install into a 489 case ?
I understand the ring gears and pinions do not interchange because of shaft and bearing size differneces, but I am not sure about the sure grip.

Lastly, what if not a sure grip, what would be recommended for installing in this ?
I have a powertrax locker in my 69 440 4 spd charger, but man is that thing loud and clanky.
Thanks in advance
 
If you're using the entire assembly...it's a touch wider, which can change things on the earlier cars with small wheel-wells. For the average car, an Auburn unit seems to work well.
 
Both sure grip types; Spicer power lock and the Borg Warner spin resistant, interchange in all three cases 741,742 and 489. I've had a change of heart for the maligned 741. Even though its pinion pales in comparison to its bigger brothers, its still bigger than a Ford nine inch! Oh and the Detroit True Trac all the way for an aftermarket alternative.
 
I swapped my Sure-grip out for a Eaton Trutrac and it works flawlessly. I changed my 741 case with 3.91 gears to a 489 with 3.55 gears as well. Mosier Engineering had all the parts.
 
OK
So a sure grip on a 741 case will fit into my 489 case and vis versa.
Thanks,
Also, Tru Track as an aftermarket, is that the same dog eared toothed as my power trax ?
Thanks again
 
The Truetrac is a limited slip unit that has worm gears instead of clutches so it will not wear out easily.
 
Yes the differentials are 100% interchangable from one case to another. 741,742&489 all swap.
 
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