Is it a gasoline only engine?
My BIL owned an old one in 1971,, it was a TD-9 ,, a diesel,,
started on gas, switched to diesel,,, the firing order was 1-2-3-4,,,
I spent MANY an hour on that thing,,,, and broke at least 6 first gear gears,,
it would break in half, if you hit a stump just right,,
The first gear gear cost $35 in 1971,, the local IH guy kept them in stock,,,
