liftmaster opener with 2 terminals-need receiver

folks. i've moved to an old liftmaster chain unit that looks as old as the hills. the last owner says it quit working years ago, that the radio unit died. the wall button still works fine. someone put an old genie intellicode receiver in but the wires were all removed. my source of info says he never saw that run either.
my problem is, this old liftmaster opener only has 2 terminals on it. hot/28 volt & common. i'm guessing that the intellicode which has 3 terminals is not compatible. which is why someone unwired it. i've rewired it every which way and can't get it to work.
does anyone know of a radio controller i can get which will work in this application??thanks/dave in ohio