1974 Dart Sport 7.25 to 8.25 swap

[76Scamp]

I have recently acquired an 8.25 rear end from a 1974 Swinger that I am planning on putting in my 1974 Dart Sport. My car is currently a three on tree A250 (I think) and a 7.25 rear end. My questions: do I need to change the driveshaft? Is the u-joint larger? If it's just a u-joint difference, is there a conversion joint to use my original driveshaft with the 8.25 yoke? I'm in no rush to do the swap because the car does still drive and is driven daily, and I also have to (want to) rebuild the 8.25 because it's a 2.45 gear. Any and all help/information is greatly appreciated. Thank you.

 

[doug 371]

you will need to have the driveshaft shortened

 

[76Scamp]

you will need to have the driveshaft shortened

I was afraid of that. I plan to also T5 swap the car eventually and really didn't want to have two driveshafts made. But if I must, I must. You wouldn't happen to know how much I have to shorten it, would you?

 

[doug 371]

not off hand but maybe you could put a want add for a factory 8.25 driveshaft

 

[72bluNblu]

7.25 to 8.25 should be about a 1.6” difference, so shorten the driveshaft 1.6”. 7.25” to 8 3/4 is about 2.25”.

Best bet is to measure it yourself once the rear axle is in, using whatever measurements the shop doing the work wants to have.