I am having the same thought. but I have a 1991 electra glide classic and can't find a 6 gal 1pc tank that I can use the original tank door and bib on.

 

Welcome to HDF from the UK! I used a 2009 Touring tank and matching tank door etc on my 1990 Glide, all bought secondhand from Ebay. The current 6 gallon tank is longer and has a more arched top than our tanks. The only alternatives are custom tanks, every one of which is likely to need suitable components, or be otherwise custom finished. I spent a long time looking into the possibilities!