I believe someone installed a suction mesh filter (looks like a spin-on filter but it's actually a 150 mesh wire gauze element). The installation should be pretty straightforward, and the parts are easy to come by. I think you have to remove the in-tank screen. Sorry I couldn't be more help. It's not a dozer.
Just ordered a external hyd. oil filter from http://www.affordabletractorsalesco.com It seem to have what is needed to install the filter to existing piping.
Our external Hydraulic filter kits, it's made to install on the return line near the pump, you cut out a 3″ section of the hard line and install the filter head with 2- compression type fittings.You will need to cut the screen off the existing hydraulic filter in the hydraulic tank, but you must keep the pick up pipe
Tommy, Im interested in your filter hookup. I just bought a used Jinma with loader. My other one has a home built hookup which clutters things up a bit.
Can you clarify where yours mounts again. I dont think there is a return line near the pump (from your last post). Or maybe Im not remembering rihgt. This is a return filter and not a suction filter, correct?