We use a good grade of 80/90 extreme pressure gear oil obtained at a local farm supply store for all of the gear boxes in our trucks. There is nothing unique about these gear boxes that cause them to need any special grades of oils. Each box has its own drain and level (fill) plug. Unique to the wrecker (referring to the M543A2 here), other than the usual transmission, transfer case, and axles, check the boxes at each end of the drive shaft from the transfer case to the bevel gear box under the center of the turntable. There is a CV joint in each that needs lubrication. Also check the bevel gear box under the center of the turntable. There are also gear boxes at the end of the hoist winch and the table rotate gear box on the turntable under the back of the hoist unit. Each drag winch also has a gear box that needs this oil, including the box on the end of each winch spool where the worm gear is and the opposite end. We use the 80/90 EP in all of these boxes.
Regards Marti
