Why won't a fuel tank from an 04-05 fit on a carburated '01? Is it just a matter of a different petcock? It's my understanding that the tanks for the 04's and 05's are the same regardless of carb or FI. Anybody?
The '04 & '05 FI and carb tanks are the same because H-D simply uses a different type fuel float setup on the carb bikes than on the FI bikes.
You can use a FI tank on an earlier carb bike by either changing to the later fuel float OR by fabricating a plate to cover the large center hole in the tank and adding a stud to the plate to secure the dash cluster. You would also have to cut a hole in the left side gas cap hole to accomodate the earlier gas guage float or simply eliminate the gas guage.
I think that when Harley came out with the FI Softails they made two different style tanks until they used up all of the non FI(carb)tanks and then simply used the same tanks on both FI and carb bikes.