I have my VIN Y 83’ Delta and am not too concerned with changing its internals out BUT, my dad offered me a rear end out of a 91’ Buick road master with a 3.23 gear + an unfortunate but useable 5x5 bolt pattern. Providing it is the same size and can bolt right in to the drivetrain; are there any constraints regarding the fact that it’s only lugging 140~150hp? I’m partially educated about this and im wondering if it will affect my RPMs in 3rd gear like highway driving? Thanks guys

 

Ok well some thing that might be different is a the actual rear end size.... 7.5 to 8.5... If this is the case a drive shaft mod will be needed in length.
The 1978-1996 should all be the same mounting points (spring perch, lower and upper control arms etc. ) The wheel bolt patterns range from 5 on 4.75 to 5 on 5 But yes other than that you should be able to swap the rear fairly easily.
gear ratio will help if you are going from 2.56 to 3.23 in low end torque and throttle response feel. BUT you will also on the other end of the spectrum loss highway top end speed also.

Jim
JD