I think that are all same thread but difference in 86-87 and 88-89 are the 86-87 has those 2 spacers that are bolted down on sides of tank. 88-89 do not have those spacers on tank those spacers were glued on fenders that is why on original 88 red fenders you see a dark black strip on front fender by your knee. All tanks are interchangeable and later tanks sold from dealer and that includes the black one sold later model tanks once the first generation models were discontinued