I am in the middle of thrashing on the Duster and swapped out the 7.25 rearend for a 8.75 rearend. I obviously have to shorten the driveshaft, but was wondering if anyone else who has done this remembers how much they had to? I am trying to compare my measurements with someone else's.

Thanks, Brian

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Flyin' Brian

74 Duster, 225, rear-mounted blow through turbo at 12psi boost, street/strip car
"Sixy Beast"

I went from a 8.25 to a 8.75 in my '84 D100. Shortened it 1.25". I think the difference between 7.25 and 8.75 is 1.75". Cost to have it shortened, balanced and 2 new U joints was $120.

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Slant Cecil

Thanks Cecil, I measured just over 2 inches but that was with the slip yoke all the way in. Does anyone know how much freeplay I am supposed to have?

Thanks, Brian

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Flyin' Brian

74 Duster, 225, rear-mounted blow through turbo at 12psi boost, street/strip car
"Sixy Beast"

7 1/4 to 8 3/4 needs a 2 1/4" shorter driveshaft.

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Joshua

Thanks Joshie225, I've been paging through my factory service manual and couldn't find the info.

This forum ROCKS, so glad I found it a couple years ago.

Thanks, Brian

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Flyin' Brian

74 Duster, 225, rear-mounted blow through turbo at 12psi boost, street/strip car
"Sixy Beast"

I've done the swap 3 times. 1.75" is the magic number for me.

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Official Cookie and Mater Tormentor.

I have used 2". I think Triangle Driveshaft is pretty close to you and does good work. Make sure he balances it too.

Lou

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Home of Slant6-powered fun machines since 1988

oh, you want to do it right....
we cut down the one from a 73 dart to convert dads a100(only for around the yard) by cutting where we guestimated by holding it up, then wrapped duct tape around the inner piece so it was at thick as the inside of the outer piece, then had a buddy weld it up, yeah, its a little rough...but it moves haha, good luck with the swap, sounds like youve got the info you need!

Thanks for the info Zilla and Lou. Can you guys tell me if your swaps were done on '67-later or '66-earlier A bodies? Or both?

Lou, Triangle driveshaft was the place I had planned on using (per your recommendation at the banquet).

I am going to re-measure (again) to check myself one last time. Sounds like I need to be around the 1.75"-2" range. I measured almost 2.175" on mine.

The 2.25" measurement seems like a lot, I wonder if the 8.75 rearend came with a 727 tranny? Is the 727 same length as the 904? I'm probably overthinking this whole thing.

Thanks, Brian

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Flyin' Brian

74 Duster, 225, rear-mounted blow through turbo at 12psi boost, street/strip car
"Sixy Beast"

I did the swap on my '76 Duster, '66 Valiant, and a '70 Swinger. All were 904/7.25" to start. I actually have the shaft out of the Duster in the Valiant now.

A 727 is approximately 4" longer than a 904.

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Official Cookie and Mater Tormentor.

Thanks Zilla, I guess that clears up any question of different driveshaft lengths between the early and late A bodies.

Thanks, Brian

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Flyin' Brian

74 Duster, 225, rear-mounted blow through turbo at 12psi boost, street/strip car
"Sixy Beast"

7.25 to 8.75 swap....I shortened it 2". $40 to cut and reweld

Update...

I ended up going with shortening the driveshaft 1 7/8". Had it rebalanced and new ujoints installed. Fits real nice, but have not driven it yet. I am still working on the rear brakes. Cost me $160 for everything. Thanks for all the responses!

Brian

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Flyin' Brian

74 Duster, 225, rear-mounted blow through turbo at 12psi boost, street/strip car
"Sixy Beast"

Cut 2 1/4" off, ballanced, new joints, $110 here for the 7 1/4 to 8 3/4 swap.

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