Gas Cap Question-71 Duster

I believe the 71 neck mates up to the inside of the fender and the 72 is fed from the outside of the fender to the tank.

Yes I've heard this as well. I'm in the same situation with my 71 scamp.

Anyone have input on this source?

www.521restorations.com/index.pl?page=allmodels&sub1=Fuel