Another Fuel tank thread - 71 Demon

The tube pictured is the length difference between the Barracuda and Duster. I just sold a 70 Duster tube to someone withe a barracuda. it was longer by the same difference as you have shown. Longer is ok shorter Not correct. Use your old one . Zinc plate it. Very easy to do at home. Use a web search. we zinc plate parts. You can polish them or let them gray/silver

The tank issue can be solved with a thicker tank pad int the front of the tire well. As stated above I used part of the old pad and folded it in half and put in front of the tire well. It moved the tank forward and it fit without being noticable.

Your cap is a 71