If you put an 8 1/4 in place of a 7 1/4 the driveshaft needs to be 1.6" shorter.
http://www.moparts.org/Tech/Archive/axle/5.html

DI listed the correct applications. This list may also be helpful...
http://www.autohobbydigest.com/tables.p ... _slip_yoke

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Joshua

other problem i ran into today is the e brake don't want to hook up does both side need to be done at the same time

No, if there isn't enough slack to hook the one side up and not the other... you need to go under the passenger side floor pan and look for a little angle bracket held by a j'bolt and nut... douse threads with PB blaster or Liquid wrench, then use a 1/2" flat ratchet (or a normal box end wrench) to loosen and allow some slack... once hooked up, re tighten the nut on the j-bolt, check the e-brake lever for proper operation and stiffness...

-D.Idiot

hey guy i found a guy that is sell one he wants 75 for this is what he said see i want to see what you guys think
I have one that is 49" to 50" center to center that came out of my 73.

I had it bolted to an 8 3/4" rear end but sounds like it might be the
right length.Its has good u joints and a automatic 904 spline on the
transmission end

i call a drive shop here and the guy said it would cost me 70 to get shorten and balance which i think is a good deal the guy that is sell the drive shaft wants 75 for his, i will got get it shorten today to 49.9 '' which i hope will be the last thing that i have to do to get it back up and run

Shortened and balanced for $70? Portland area? If so what shop?

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Joshua

no i am in Eugene the shop name is Drive Line Service of Eugene is 70 good and i do want is shorten to 49.9 in right

That's a good deal. Yes, that's the length.

Be aware that they will try and talk you into new U-joints and may tell you that the yoke is sprung or some other term to get you to buy more new parts. If you've got the time ask for an appointment so you can wait while they do the job. Call it cynicism through experience.

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Joshua

will do i can wait until Friday i have nothing to do

hey guys i got my drive shaft cut and the also did not try to sell me any other parts for it i just have little stuff to do than i am done but the big stuff is done with thanks for all the help i am pretty sure i would not know all the stuff that you guys do so again thanks

The last time I had a driveshaft cut and balanced the guy charged me $30. He's been doing driveshafts and rearends since the late 60's. Done some work for me a few times over the last couple years.... I'll have to call and see if the price went up.

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When I swapped the 8-1/4 in place of the dead 7-1/4 rear in my 90 Dakota, I paid $48 for cut/balance of the drivesvaft.