went to virginia from detroit to pick up a car,904 trans let loose in the truck when I got there. $1600 for a rebuild, no old parts in the salvage yards .forget it. back home in detroit,I am going to upgrade to a 727 trans, so I need to get everything ready for a quick swap next weekend.i have the 727 yoke, how much to shorten the driveshaft? 904 trans is in vehicle,727 is it's replacement.

This trans length info was posted a few years ago by member Feets. It should help but I don't know if the different slip yokes make a difference. Hopefully someone with more knowledge will chime in.

A 727 is 4" longer than a 904.... So going from 904 to 727 you're driveshaft needs shortened 4"

The driveshaft lengths are listed in the White Books, so if you just list what car and rear end you have it will be real easy. Also, there are different diameters depending on your combination.

Do yourself a favor and install the driveshaft yoke into the tail of the trans, push it in till it bottoms out.
Pull it back out 3/4 to 1" from it's bottomed out position in the tail of the trans and measure from the center of the ujoint cup on the front of the drivshaft to the center of the yoke that the rear ujoint sets in and that would be your length.
You can just cut 4" off but you might want to check the actual length.
Once it to short its gonna stay that way.
You will want to do this with the cars rear end on jack stands not with the rear end hanging..

I have had 3 drive shafts shortened for different cars. the older car drive shafts can not be shortened. they are double wrapped, meaning there is an inner shaft, a layer of vibration dampening rubber and then another tube on the outside. the easiest thing to do is get a drive shaft from a 70's/80`s truck or van and have it shortened. although they are larger in diameter, they are not double wrapped and can be shortened.

*sorry I just reread that you are swapping trans. in a truck

I have a spare driveshaft, and I'll get it cut down, can't do the measure thing, the truck is 9 hours away and I need to drive there friday night, swap the trans out saturday, drive home sunday. I don't see getting a driveshaft done in a couple hours.Thanks,

For what it's worth, I had 4 inchs cut off the driveshaft, and all is fine,made it back to michigan. Thanks.