It's possible but if your state doesn't require special inspection then the body shop is less inclined to be spot on. Most people don't take measurements of their panels. But also, you gotta measure the unibody itself with the same tools. The panels themselves might be off but the body might be fine. Also, after ******* with a car for hours, some shops will just give a car back that's slightly off. 3/8" of an inch shouldn't make much of a difference in regards to collision performance.

 

Just a heads up the same thing happened to my acura. My girlfriend crashed it, bent the front subframe and the unibody. Some shop had it for a year, replaced subframe and lower control arm ball joints ect. The car never drove strait, always pulled one direction, and burnt up tires on the inside real fast. And my unibody was about a half inch off also. If the unibody is bent behiend where the rear subframe is mounted to it, you should be fine... but if the unibody is bent in front of or where the subframe mount, it may never drive right. Just my two cents, I'm really here because I found out my anit sway bar broke my subframe yesterday(which was already welded once). So I will be doing a rear subframe install also, I hope everything lines up for you!