According to the VIN it's an '89 (K) Pioneer 2WD 4.0L, it's not a 5001-6000 GVWR, the following is from the '90 FSM, '89 had the same codes.
It might have a D44, my '89 2WD Pioneer has a D44 with the 'F' designation, my '90 2WD Sportruck has a D35 also with the 'F' designation.