I don't know if they are disputed or not, but the '78 Montesa VB250 and 360 are virtually identical to the '77 models. I think that they are allowed in the AHMRA's Historic class (which M.A's pre '78 rules were copied from). The '78 VBs had remote reservoir shocks compared to the '77 model piggybacks and had a small muffler added to the end of the pipe. Also, the '78 model Husky CR250 and CR390 could also be possibly be allowed into pre'78 class, if a '77 model swingarm was fitted, as they are also pretty much unchanged from the '77 models. Apart from the swingarm, the only other differences that I know of are the tapered roller steering head bearings on the '78 frames and the exhaust pipe (which follows the same lines as the '77 anyway). Also the '78 AMX390 Auto Husky could also be considered for inclusion into the pre '78 class, as you could have easily built one of these from existing parts in '77.
