Do I need to change out driveshaft on a 318/904/8 1/4 to 440/727/8 3/4 swap?

[dspaulding70]

I know that the yoke would be different but will the U joints be the same and can the driveshaft be used?

[Ghoste]

You will need to change the driveshaft and you might as well upgrade u-joints while you're at it.

[pettyfan43]

Yeah the 318/904/8-1/4 shaft will be longer. I got lucky on my 66, it came with the poly 318 but had a 727 and 8-3/4 so I could just stick the original back in.

[Chatt69chgr]

http://www.dodgecharger.com/forum/index.php/topic,23738.0.html

The above thread should answer some of your questions.  Basically, the driveshaft you have is approximately 4 inches too long and uses 7260 yokes.  7290 yokes would be preferable.  Also, probably would be better to have a 3 inch or little larger diameter driveshaft.  I would have one made up by someone locally---------or you can buy the one from Mopar Performance that you cut to length and have the weldable yokes welded on and then balanced.  Check your yoke on your 8-3/4 to see what it is.  Measure the inside dimension between the "U".  If it's 2-1/8 inches its a 7260.  If it's 2-5/8 inches, it's a 7290.  And there are two different 7290 yokes.  One is fine spline and one is coarse spline (in case you buy one for the rear end)---you can tell the difference by the attaching nut size.   The transmission slip yoke in 7290 version can be found at most any junkyard on a C body like a New Yorker for example.

[vert]

There is also a conversion U-joint that works with the 2 1/8 by 2 5/8, so you can use the larger driveshaft with the smaller yoke, or vice versa.