Rear End Swap 7-1/4" to 8-1/4"

I removed the yoke from the driveshaft this evening, stuck it in the trans and lined up the wear marks with the trans seal so it is sitting in exactly like it was before the teardown. Yoke sticks out 3-1/2" from the end of tailshaft housing(not the seal) to the u-joint hole centers. Measurement between both yokes came out to 50" from center to center, about 1/4" shorter than I originally guestimated.

Difference could be perhaps because the car sits 3-4" higher than it once did. Since there is about 5" of trans shaft contacting the inside of the yoke at 50" I feel comfortable with this measurement. If it comes within 1/2" plus or minus I am not sure there would be any consequences. I can push the yoke in about 2" into the trans before it bottoms from where I intend it to mate up with the trans.

Anyway, this was the easiest part of the job. Now tomorrow I will drop the driveshaft off at the machine shop and let them do their thing.

*****Edited in:
The driveshaft actually measured in at 51-7/16 not 51-7/8, that's why my measuement under the car was off by about 1/4". Never trust your memory, always write it down. So going off of my original corrected math, 49.84 would be the center to center guestimate. Underneath the car measurement came in at 50". Sanity check completed. Always do both measurements.

So to recap for anyone who does not want to measure or just wants to find a donor shaft the correct length before starting the swap:
For all 108"(Duster, Dart Sport, Demon, Some Valiants before 73?) wheelbase A Bodies with a 904 automatic(or any other trans the same length and shaft depth), an 8-1/4" rear end, 50" from center to center is the number. I will measure the yoke again and post that because I have heard not all are the same length. I am pretty sure mine was 7" from u-joint center to tip.*****