I thought Doc had a post that explained how to properly measure how much the driveline needs to be shortend but I can't find it.... so what's the right way to do it guys? Or should I just not measure and shorten it 1 3/4" as that is the numer I have seen all use when they go from 7.25 to 8.75" rears?

I've done 2 and that is the number I used both times.

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Official Cookie and Mater Tormentor.

$80 bux to shorten a driveline (includes balance) wow.. didnt know itd be that much. Ah well, I'll take it to the shop this weekend to lop off 1 3/4" then, I trust you slantzilla
Say, with the "small" yoke, the u-joints are the same as the 7.25" rear ones, right? That'd be cool if I could reuse the u-joints.

3 out of 4 of the 8-3/4 yokes that I have are the "small" 7260 u-joint. Only one is the bigger 7290.

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Official Cookie and Mater Tormentor.

Right, I just didn't know if the 7260 yoke on the 8 3/4" was the same as the yoke on the 7 1/4". Just tryin to cover all my bases so I don't encounter any surprises.

It's always better to ask questions before you plunge headlong into the unknown. Maybe someday I'll learn to do that.

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Official Cookie and Mater Tormentor.

I just swapped the 7 1/4 in my Duster for an 8 3/4, and I shortened the driveshaft 2 1/4". It worked out perfect.

A suggestion though - why not take this opportunity to replace the ujoints (unless they are pretty new) since you already have the driveshaft out?

Be a good time to replace the rear seal on the tranny too.

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It's a Slant thing. Even I don't understand.

1974 Duster, EFI /6 soon to be turbo...

Get that Monkay! Get that nasty thing!!

"Measure twice, cut once", that's what dad always said.
Measure with the car at ride height, no wheels "hanging" while supported on jackstands.
Push the slip yoke in all the way, then pull it out 3/4 to 1 inch, then measure. outer edge to outer edge of the U-joint "eyes" minus the diameter of the eye will give you a center to center measurment.
DD