These engines use 2 threaded holes on the bottom of the oil pan to secure the right side of the engine while the left used the tabs all big block Kohler's of Wheelhorse I've seen are like this from 60's to late 90's I thought the same thing when I first bought my first Wheelhorse took be untill I removed the engine to rebuild it to realize they have 2 bolts under to secure
These models were introduced in 1962 determined by the suffix 2 in the model numbers.
ST-302 fits 1960 models 400 550 and 1961 models 401 551 tractors
ST-3072 fits short frame tractors starting with the model 701
Why did I post this? Because I wondered what the difference was and am sure others have also. It is explained in the manual.
Thanks, but I already pulled the trigger on a new one. The correct one measures 8.75" wide and 13" pin to pin. If you have one that size and have no use for it, I'd take it off your hands to have a spare.
I have actually noticed many times in photos that same issue of people having mule belt on wrong pto pulley and always wondered how many years has someone mowed with it like that?