driveshaft length questions

[superwade57]

so i im to the point in my t56 swap where i need to select a driveshaft, everyone has been talking in other posts about shortening a driveshaft or custom length, by accident today i discovered a couple driveshafts that may work from other stock gm trucks.... today at work one of the work trucks had a pinion seal failure, followed by a rear yoke failure, the truck is a 96 2500 4x4 with an NV4500 rear driveshaft measures 55 inches center to center, the donor truck for the spare yoke was a 92 4x4 2500 with a 700r4 drive shaft measures 52 3/4.

heres my question.... on a stock ride height t56 swap into a 2wd swb with the tranny yoke in tight to the tranny the distance between tranny and rearend measure 56 inches, how much play should be there with the driveshaft installed? should the yoke have an inch to move in or more or less?

the other driveshaft fits in because i have a flip-kit to install which moves the rear end back 3/4 from stock, i would need to install and measure but seems to me that if i reverse the flip brackets to move the rearend forward 3/4 inch and the drop its self assumedly moves the rear end 3/4 nearer the trans would the 52 3/4 driveshaft work for me? thats a gap moved to approx. 54 1/2 center to center with the tranny yolk pressed tight to the trans so at ride height the yolk would need to be 1 3/4 in out from tight. is that to much out? should i find a 55 in driveshaft and install the flip kit normally or am i ok to use the shorter driveshaft and reverse the flip brackets? btw the shorter driveshaft is free i need to buy a longer one