Onan 16.5 hp twin

[BrownA]

I finally decided to part with a Gravely tractor I recently picked up. It has the Onan 16.5 hp twin cylinder engine. It sounds like the more I read about them engines the quicker I want to sell the tractor ( plus it's not a simplicity ). What can anyone tell me about those engines ? It's on a 1979 Gravely 4 wheel tractor. I was just wondering before I sell it. Any help is appreciated. Thanks, Al