Ok, back at boat, took door apart (stripped screw, drilled out, broke key in lock, shoulda removed it, not too much blood spilled, but the whole thing is a dirty mess).
Found Boat Outfitters advertise these door trucks, but no stock..... found Flounder Pounder Marine (this is true) and they have them!!!
https://www.fpmarine.com/Sliding-doo...20a%2023mm.htm
Boat takes two of the 23 mm and two of the 25mm trucks.
Rod