I have a Ford mustang tank that is practically made for this application. I just trimmed a slight amount of frame width off the bottom of my frame rails, and it slides in perfectly. The C channel on my frame actually widened a little towards the rearend. I didn't have to trim very much. I removed my rear cross brace rivits, and made it removeable and used bolts to install it back in place. The year was 1968-1970 I believe.
