The round part of the casting with the drain plug. Should access from the opposite side of the tractor from the pic. Open the drain plug first, allow to drain, then remove the 2-3 bolts holding the cover, followed by the screen. Then remove the drain plug farther to the rear, then replace the screw on filter in the pic. Make sure you clean the screen from the inside out to push debris out. And BE CAREFUL not to damage the screen since even the cheap places think the thing is made of gold. If you need parts check hoye listed under the yanmar section, much cheaper than JD. I think the 1050 is either a yanmar ym3300 or 3600. The 1st 2 digits are the Pto HP and look under d models if you need 4wd parts.