Lost on what to do with rear end - trying to swap

[Old Truck Man]

use the five hole rear from 73 up pickups on leaf spring GMC trucks. You simply weld the spring perches and shock mounts from the 6 hole rear on the newer one. On the newer trucks one shock is forward and one shock rearward. Of course you can have your present axles drilled If you have a 6 lug rear. not a option on the 8 lug rear. But you still have to convert the brakes. The later 73 up rearend gives you a larger range of rear gear ratios and a better choice of rims.