Excellent box gives little trouble .
Beware that the early 4 speed & H shift patterns are obsolete and service parts like the selector fingers are getting hard to find.
The ride on racers seem to like them so if they can take 40 Hp your motor will not give it any trouble.
Pull it down and check the imput shaft some are bushed and some run direct on the case and usually require machining to take the bush or replacing.
early model cases are hard to come by.
Take the current model Tecumseh brake which works on the layshaft and is prone to clogging and jambing on.