i have a 86d150 with a very sick 833 in it transmission is not factory installed i think it is a 70-74 b/1 body long tail shaft has 2 shifter mounts my question is cross member dont look to be moved from factory placement so is the 70-74 the same as what would be factory in my truck i havent found any tech relating to my truck trans

the trans mount had the same location, it was the shifter mount the was farther back on the tail shaft.

This is correct, on the B/E tranny, trucks used a plate bolted to one of the pads to offset the shifter correctly for that set up...you should be able to transfer everything (plate, shift rods, shifter) over to another tranny, but B/E trannies are kind of $$$$, also some B/E trannies had the 'hemi box' which had 18 splines on the input shaft compared to the standard 23 splines found in everything else (save some NP435 boxes).

-D.Idiot

cool mine has bearing noise and yoke is flopping around in tail shaft still shifts good but has bad vibration from drive line flopping around havent removed drive line but i am sure yoke and shaft are chewed up i just got truck dont know how long its been like this

Is the trans a O/D unit check for a aluminum case they did have a tail shaft with duel shifter mounts, bushing in tail shaft is replaceable can be replaced without pulling trans apart,may need new yoke also.