I went to NAPA today to see if I could cross reference the filters for my 4310. We looked under JD 4310 and they had a list of all filters that they make for the 4310. They had a power steering filter listed, but reading my manuel I did not see that I had a PS filter. Does anyone know anything about this filter that would mind passing the knowledge along. Also, I was trying a cheaper filter for the side suction filter. FYI NAPA filters were higher price than at JD. The salesman said no way that he was higher than JD, and to bring the prices of the JD invoices in and he would beat the prices. Thanks for the responses.