Well , the good news: all the replacement filter elements we're aware of are mfgd by Stanadyne, just sold different labels.
Bad news #1: Most places the filters are 15-25 dollars.
Bad news #2: The filter elements are not easy to replace. You should follow a procedure of draining, removing, cleaning , and replacing the element . The black plastic bands on the top and bottom of housing are 'nuts' to secure filter within top , and heater within bottom. I needed a strap wrench to initially remove my first filter. [this is the hard part--examine element carefully. note different size slots in cap. the slots index with tabs in filter housing. Each of the first two attempts i made at replacing the element i destroyed the seal on the new one--so buy a second new one as insurance to have on hand if you're as clumsey as i am].When the element is removed , check for the cylindrical nylon filter screen . make a note of what you found.
Ok , after install new element and snug top securing ring, then need bleed filter housing from the hose-nipple atop the button-nut(?) on top of the filter element. LiftPump needs energizing for this part.
You can "search" in this forum for more hints. Good luck , and Happy Thanksgiving.
tom m
'95 6.5td 4L80E 3500/srw p/u