See Figure 1
Multipurpose gear lubricant meeting API GL-5 requirements or MOPAR hypoid lubricant can be used in conventional differential axles. Limited slip units, except in the 9 3 / 4 in. and 10 1 / 2 in. axles, must use MOPAR hypoid lubricant. A MOPAR friction modifier additive is available to cure chatter and noise in these units.
The 9 3 / 4 in. and 10 1 / 2 in. limited slip units must use MOPAR Sure-Grip lubricant. Gear lubricant viscosity depends on the anticipated temperatures: SAE 140 for above 90°F, SAE 90 for normal conditions (10-90°F (-12°-32°C)), and SAE 80 for below 10°F (-12°). The factory fill is normally SAE 90. Multiviscosity lubricants may be used. For more information on rear axle identification, please refer to the serial number identification information earlier in this section.
See Figures 2, 3 and 4
To check the axle lubricant level, remove the axle filler plug with the truck parked on a level surface.
The 93/4in. and 101/2in. axles used from 1976-80 (300 series) have a pressed in rubber filler plug instead of the usual screw in plug.
You can use a finger for a dipstick, being careful of sharp threads. If necessary, add lubricant with a suction gun. The lubricant level should be 1 / 2 in. (13mm) below the filler plug hole on 8 1 / 4 , 8 3 / 8 and 8 3 / 4 in. axles, or at the bottom of the filler plug hole on all the rest.
DRAIN AND REFILL
See Figures 5, 6, 7 and 8
Axles on Dodge and Plymouth trucks are not equipped with drain plugs. The old lubricant must be drained by removing the differential housing cover. Most 1972 and later models no longer use a paper gasket under the rear axle cover. Instead of the paper gasket, a bead of RTV silicone sealant is now used in production. The sealant is available for service.
Sealant should be applied as follows:
- Scrape away any remains of the paper gasket or old traces of sealant, as applicable.
- Clean the cover surface with mineral spirits. Any axle lubricant on the cover or axle housing will prevent the sealant from taking.
- Apply a 1 / 16 - 3 / 32 in. (1.59-2.38mm) bead of sealant to the clean and dry cover flange. Apply the bead continuously along the bolt circle of the cover, looping inside the bolt holes as shown.
- Allow the sealant to air dry.
- Clean the carrier gasket flange (if solvent is used, allow it to air dry). Install the cover. If, for any reason, the cover is not installed within 20 minutes of applying the sealant, remove the sealant and start over.