This is a close-as-possible copy of a fuel tank for a Con-Cor ALCO PA powered locomotive, 2nd and 3rd generation ‘Kato’ plus 1st generation ‘Chinese-made’ models.  This will not fit a PA dummy unit as they did not have a separate fuel tank which is part of the chassis.

It is available here.

The fuel tank is available in several materials including black strong and flexible and white strong and flexible, FUD and stainless steel.