im wanting to put a 12 bolt posi chev rearend in my factory 57 chev truck frame is there a rearend that will fit without modifying the rear too much i have a 70 monte carlo rearend ,but it looks like it would be alot of work to swap in has coil springs or,would a 69 camaro 12 bolt rearend be a better choice as i know where one is located or does anyone know of a better choice of rearends to use same length etc.