This is the new sending unit we installed in our car. Available from Mustangs Plus, it's a direct replacement for the original. Basically, '65-'73 Mustangs came with three fuel tank sizes: '65-'68s had a 16-gallon tank, '69s had a 20-gallon, '70s had a 22-gallon, and '71-'73s went back to a 20. We installed a larger 22-gallon tank in our '69 for an article in the June '04 issue, but at the time, we reused the car's original 20-gallon sending unit, which affected gauge accuracy. We wanted to install a sending unit for use with our 22-gallon tank. Also note that it is possible to install the 22-gallon tank in any '65-'70 Mustang. The '71-'73 tanks install from underneath the car so the upgrade to a 22 isn't possible.