The engine oil filter will be no problem. If you are near someplace that sells filters for diesel equipment, you may be able to get a good deal TruckPro, or somebody like that comes to mind. As for the Grasshopper hydraulic filters, I have never been able to come up with a proven interchange for those, so I have always bought them from the dealer, knowing full well I am getting screwed on the price. Maybe someday I will sit down with a filter specification catalog and find my options for the correct size filter, and them try figure out what micron rating I need. As for belts, at least when it comes to deck belts, it's been my experience that even high quality aftermarket belts just don't hold up like the GH OEM belts. The life of the OEM deck belts far exceeded what I was able to save by going aftermarket. Lesson learned.