Cut the ends off the 8-3/4 to use on the dana. Cut the dana so the tubes are the same length to fit your 8-3/4 axels, use open rear till you find a posi (any Dana truck rear will most likely have one in the bone yard) The axels will be the weak link till you buy the 35 splines and spool or posi. At lest you’ll be going up in the right direction money wise. 8-3/4 and Dana driveshafts will be different lengths so don’t buy twice. If you haven’t got the Dana yet scrounge the yards till you find a truck rear with the posi and 4.10 gears usually $200 around here. Install ends,axels, done. Get the driveshaft too.