I have done several frame replacements using the 83-90 s-10 standard cab,long bed chassis......The wheel base is about 1/2 inch difference.There is a company in california that makes all new body and bed mounts for this but I've allways made my own.I heard the ready made makes an easy swap.The rear end out of a 4x4 s-10 blazer is 53 inches hub to hub and the late 60's early 70's nova ,camaro,monte carlo,etc. is 54"......These work best just check the offset on the wheels so you don't get bedside rubbing..Same with the front to get the look of the tires sitting right in the fender.....use the proper offset on the wheels and everything works good......Some modifying of the front and rear frame rails are necessary as is making a radiator saddle mount.There is usually a small amount of modifying of the saddle needed to clear the steering box......