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8 1/4 to 8 3/4

ddpsnake

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71 Satellite 904 tranny I have the 8 3/4 ready to go in, now going from a 8 1/4 to 8 3/4 what are the chances i will not have to cut the drive shaft? with the 8 1/4 now i have only about an inch i can push into the tranny to remove the drive shaft.My fear is when i do the change over and have to cut balance the drive shaft, with all the lock downs i will not be able to find a shop.has anyone on a 71 sat/roadrunner done this what did you find out . thanks again gents.
 
I did this same swap in a '76 Duster and I didn't need to cut the drive shaft. Your results may be different depending if your drive shaft was a little on the long or short side to begin with.

P.S. - I'm about to try it again in a D150
 
I think you could take a piece of pipe which matches the U-joint cup diameter turn the pinion so it's parallel with the axles and put the pipe in the pinion. (where the u-joint would normally go)
Take some measurements to see Centerline of pipe to axle away from the carrier. Do for each carrier and you should be able to get within an 1/8" or 1/4" between the two.
Just an idea/suggestion.
 
The thing is my new 360 is still on the engine stand hopping someone has done this on there 71 thanks tho.
 
Two factor to consider. 1. Yoke side to match u-joints. 2. 8.75 will require a shorter drive shaft. Old unit may fit but will jam your transmission because the drive shaft must allow for rear end movement up and down during normal driving.
 
I thought I could help out with the 1971 shop manual, but I can't even find a 904 & 8 1/4 combo. But for what it's worth, the Fury segment lists the same driveshaft length when used for either of those two axle types.
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