[simonclay]

Yj's did come with a 15 or 20 gallon tank. BUT they were the same exact tank. The fuel filler was longer in the 15 gal, which only allowed 15gal to be put in vs the full 20 gal.

And by "fuel tank assembly" I think you mean fuel pump (?). If that is the case I wish I could help, but I don't know much about it.