I am going to change the transmission oil in the zero turn. It has the Hydro Gear ZT 3400 transmission. Hydro Gear 52114 is the filter number. I was going with them for the filter but some of my research says their filter is made in China. I don't mind paying more for an OEM filter if made in the USA but China? I have read most of Stens filters are made in the USA. Stens number is 120-738. From what I can tell the specs are the same . What filter would you use on a ZT 3400 transmission? In case you want to know I am using M1 15/50 for the oil.