Ideally you save the original cover plate after installing the pump, but that seldom seems to happen. The PTOs are generally standardized as SAE A, B, or C. If you can figure out which you have, google or your local hydraulic shop should be your friend. And itís worth emphasizing your local hydraulics shop. Hydraulics are everywhere, as are hydraulic shops. Most of us just never know they are there. Hunt around and you will probably find one near you. I recently replaced the pump on a piece of construction equipment and a local shop was able to get a replacement for about half the cost of the equipment manufacturer. And itís the exact same Eaton pump. This stuff is almost all off the shelf commercial stuff.