I have readily available a 1990 300zx non turbo differential ive been reading up on swaps on an s13 and everywhere i read that u need a new rear or something what is this and what car should i get one to complete the install? any thing helps thanks

 

Huh?

With the VLSD from the Z32 300zx n/a and the axles from a <94 Infinity J30 you can bolt the rear end in and have a cheap LSD...