3rd gen Fuel Filler Neck

[ODZKing]

OK, I uderstand there is a difference in filler necks from 71-74.
Part numbers are as follows:
1971 = 3466426
72 (up to 2/72) = 3466330
72 (after Feb) = 3642126
1973 and 74 = 3726073
I checked, none of the numbers superseded.
It makes sense that the 73-4 would be longer due to the bumper sticking out a bit more.
But I would like to replace mine as the end is chewed up and no one has one new. And used seems to be a crapshoot as people say they're the same.
Must be a difference ... anyone know for sure.