It looks sturdy enough from the pics. Is the gearbox leaking oil? Why is there a strip of white tape on the corner of the deck? Is the wheel assembly/forks straight or bent (I mean bent, not "built to sit at an angle") Also, this looks like a shear pin unit. If you are doing mostly grass and light brush, this is probably OK; if you are hoggin down heavier brush, small trees and/or working on land with lots of hidden obstacles (rocks, pieces of iron, etc.) you might want to hold out for a unit with a slip clutch (or be prepared to retrofit), otherwise you'll be off and on the tractor to replace pins.
BOB