i bought a 60 horse mercury to upgrade my 40 horse nissan i was told it was a 1992 but i want to be sure before buying voltage regulator . the lil plate on transom mount wasnt clear so i sprayed it with some industrial cleaner and let it soak and well now its no help at all it dissolved . where else can i find the serial numbers on motor . p.s. the head is brand new so that want help 