Are 1965 thru 1968 and 64.5 Mustang fuel tanks interchangeable?
yes. in fact if you want to get more range you can install a tank from a 69 or a 70 mustang. through 1968 the mustang used a 16 gallon tank. in 69 that was changed to a 20 gallon tank and in 70 that was changed again to a 22 gallon tank. a couple of minor mods need to be done to put the larger tanks in the earlier cars, trim the filler neck and change the tank filler neck angle slightly, but these are easy mods.