IIRC, they placed a plastic shield between the tank and the differential to absorb the impact. The tanks sometimes had a tendency to split on impact. My sister had a 71 Pinto with the 2 liter and a 4 speed. She got rear ended at least once if not twice in that car, but it never caught fire. I do remember the shifter pulled out of the transmission on a couple of occasions though. It was a decent car that she drove for a few years before buying a Beetle.