Usage:
D20D (9MG),
D250D (6NG) Articulated Trucks
Description of Change: Four holes have been added in the web that is adjacent to the interaxle differential inside the transfer gearbox case. The four holes prevent air pockets and improves oil flow inside the gearbox. The improved oil flow prevents pump cavitation and also makes checking the oil level more consistent.
Adaptable To: The added holes are effective with D20D (9MG106) and D250D (6NG199) Articulated Trucks and can be added to earlier trucks by using the following method and illustrations.
1. Remove the tractor axle using the method given in the Service Manual.
2. Drain the oil from the transfer gearbox and remove the interaxle differential.
3. Mark the location of the holes using the dimensions given in the illustrations. Drill the holes using a 10.0 mm (.39 in) drill.
Illustration 1. Location of the four holes. (A) 60.0 mm (2.36 in).
Illustration 2. Section A-A. (B) 30.0 mm (1.18 in). (C)35.0 mm (1.38 in).
4. After the holes have been drilled, make sure to clean the case to remove any debris from drilling the holes.