I think it depends on how thorough you want to be, HD. If you're counting Sandstorm and Springer, then I guess most of the '86 toys had clear variations, did they not?

Hot Rod - metal/plastic feet
Kup - metal/plastic wheels
Rodimus Prime - rubber wheels metal feet/plastic wheels and feet
Combaticons - metal/plastic chests
Hot Spot, First Aid, Blades - metal/plastic chests
Predacons - metal/plastic parts
Metroplex - rubber wheels chromed legs/plastic wheels and bare legs
Ultra Magnus - um... various differences in paint, rubber, metal, plastic and chrome.

Oh, and 1984 Optimus Prime with a grey Roller and metal trailer is a variant (I don't know if they were all pre-rub signs). Plus Pepsi Prime and purple Roller.