This is interesting. In my 26 years of selling and servicing Mitsubishi tractors, I had never run into the rectangular head lamps. Then last year we bought a salvage tractor that had those headlamps and I thought someone had installed a Bolens Iseki hood on it. Two months ago I bought another for salvage and it had them too. With your post and the serial number you list, I've concluded that it must have been a change late in the model run, say 1989, 1990. Bill