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7 1/4 to 8 3/4 swap
https://www.slantsix.org/forum/viewtopic.php?t=12959		 Page 1 of 1
Author:  sick6 [ Thu May 12, 2005 7:33 pm ]
Post subject:  7 1/4 to 8 3/4 swap
I recently swapped in an 8 3/4 for my 75 duster. (489 case). I know the driveshaft needs to be shortend, I have heard both 2.2 inches and 2.5 inches.

so, since this is a popular swap, how much did everyone need to shorten thiers?

where did you get your "adapting" u-joints from, or did you use a different drive shaft, or some other item changed?
Author:  imnoisydart [ Thu May 12, 2005 10:08 pm ]
Post subject: 
I think it's 2.5
I used to find other driveshafts when I used to do this,
but recently I just had the one I had shortened by a
driveshaft shop- think it was $50. Chances are your U
joints will be fine unless you have the bigger yoke, in which case
you can get a conversion adapter Ujoint (available at NAPA)
Author:  Patrick Devlin [ Fri May 13, 2005 3:38 am ]
Post subject: 
I don't remember how much I needed to shorten mine, but it's always a good idea to measure anyway. My 8 3/4" rear has the small yoke for the small u-joints like used with the 7 1/4" rear.
Author:  69 Dart MI [ Fri May 13, 2005 4:13 am ]
Post subject:  2.5 inches
I had 2.5 inches taken off of my drive shaft when it was swapped from a 7 1/4 to a 8 3/4 rearend. The shop sent it out to get rebalanced after they shortened it for me. I can't help you on the ujoint question.
Author:  slantzilla [ Fri May 13, 2005 12:10 pm ]
Post subject: 
I've done this swap twice. 1.75" works very nicely. :shock:
Author:  sick6 [ Sat May 14, 2005 7:54 am ]
Post subject: 
okay, so two votes for 2.5 and one for 1.75.

anyone else have some size recomendations?

I have the larger yoke, so I will need the adapter u-joint. anyone know a part number off hand?
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