Also used on those nice garden tillers with reverse, like the Troy-Bilt Pony.
I agree with massacre on the get-a-single-pto sump cover and a standard cam gear idea. Check fleabay or wherever you like, they should be easy to find and for low cost.
For search terms, the nomenclature is:
Cover Assy-crankcase, part# 297602
Gear-cam, part# 212733