Nahh you're right mate, later ones were LC, maybe the MX is the clue...I dunno
heres another, they have different wheels to the LC's too
http://www.google.co.uk/imgres?um=1&newwindow=1&sa=N&hl=en&tbm=isch&tbnid=y-S_FNCxwblk-M%3A&imgrefurl=http%3A%2F%2Fdatabikes.com%2Finfophoto%2Fyamaha%2Frd_80_mx-1983.html&docid=jER3xPod31rfxM&imgurl=http%3A%2F%2Fdatabikes.com%2Fimgs%2Fa%2Fc%2Fj%2Fr%2Fn%2Fyamaha__rd_80_mx_1983_1_lgw.jpg&w=640&h=478&ei=XagbU4S3LMaThgeIvoD4Aw&zoom=1&iact=rc&dur=4781&page=1&start=0&ndsp=16&ved=0CFkQrQMwAA