That tiller looks like it can be offset left or right to a certain extent. (Nice feature) Maybe missing an "indexing pin" that could lock the current location in place (looks like a slot or opening in the rear square tubing framework for that purpose?).
I'd guess there would be some type of identification/model #'s on the gearbox that could be used to locate parts for it? Other than the framework....most other parts would be pretty generic. ie: bearings, chain, driveshaft, etc.
I have an older chain/gear drive tiller that was badly worn. New weld on hub and gear sprocket along with a new chain and it's back to almost new again.
There's also an outfit that sells every kind of tiller blades for all makes, models, applications.
Add a slip clutch to it, like
@Grandad4 mentions, and you shouldn't have much issue with it.
If you can get it for a reasonable price......I wouldn't be scared of it!!