Another curiosity question, are you in the US?
Here, the '85 was a 700cc, due to a tariff tax, then in '86 it got bumped up to the 750.
Those earlier Vulcans had the most differences as compared to the others. Mostly, air assisted front shocks and turnsignal cancelling, as well as the smalled diameter cylinder sleeve in the 700, ofcourse.
Some of the other differences are square to round front brake master cylinder cap, aluminum to chromed parts, black painted engine (just on the '85) and wheels (just on the '85 & '86) and a slightly different cover on the seat.
Otherwise, most parts are identical.
AKA: Tim & 'The Adventure Cycle' VROC #24567, NEVROC, SteelCity VROC
"When life throws you curves,
Aim for the apex."