Denny's mounts allow for adjustment, I don't recall how much. Maybe an inch. I initially had them on the engine so it would be as far back as possible. That proved to be too far back for me. I have my main engine harness connector on the firewall and it was just too close to work. It also put the valve cover very close to my already trimmed steering column tube. I'm sure other applications, the rear most position would work fine. I feel like I have it very close to where the small block was. I didn't take any of those measurements to confirm.