I used a 1972 Mustang fuel tank on my 51 panel truck.
Fits perfectly between the rails.
You have move And weld up the filler neck to where you want it.
Made my own straps.
In my case I placed the filler well in floor on. The right side.
I believe 71-73 Mustang tanks are the same.
Used an Autometer fuel sending unit and gauge.
Worked out great.
20 gallon tank fed the 455 Buick Stage 1 motor.
Hope that helps.
