I picked up a T5 yoke from someone, they're supposed to be a little stronger than the stock AOD ones but if you get one with a trans I'd use it. I looked at my C4 yoke and have read of others cutting ~1"-1 1/2" off the end of the yoke so it doesn't bottom out.(it's not splined for the last 2 5/8" of the pipe towards the trans).
T5 yoke 5" long and 5" splined;
C4 6 1/2" long and 3 7/8" splined, when cut say 5" long and 3 7/8" splined.
When you install the yoke (either) you are supposed to slide it all the way in, then pull it out 3/4"-1" to allow for
suspension travel. If you use the C4 yoke this means you will have ~2 7/8" of splines engaged when level, less at
suspension travel/ droop. With the AOD/T5 yoke you will have 4" when level, this is why I preferred to use the T5 over the C4 and not wanting the headache of cutting it, chamfering the end, etc. Your choice.
I plan to measure the driveshaft last, once the trans is mounted and i can get a level measurement with the yoke pulled out 3/4"-1" and measure from center of Ujoint cup on yoke to center of Ujoint cup on differential. "Carefully measure the distance between the centers of the front and rear u-joints. Double check the 3/4" to 1" free play in the slip yoke and measure again. Measure twice" from Shaun at SorT website.
The original cross member will hit the trans pan if you try to use it so you'll need to modify it significantly, get an aftermarket on or have one fabbed up.
Jon