RAM 1500 Owner's Manual page 783

For 1500 Model axles, the fluid level should be even with
the bottom of the fill hole (within 1/4 in (6.4 mm) of edge
of hole) for the FDU215 HD front axle and C235FE rear
axle.
For all 2500/3500 Model axles, the fluid level should be
1/4 in ± 1/4 in (6.4 mm ± 6.4 mm) below the fill hole on
the 9.25 in front and 3/4 in ± 1/4 in (19 mm ± 6.4 mm) on
10.5 in rear axles. The 11.5 in rear axle level should be 1/4
in ± 1/4 in (6.4 mm ± 6.4 mm) below the fill hole.
Drain And Refill
Refer to the "Maintenance Schedule" for the proper
maintenance intervals.
Lubricant Selection
Refer to "Fluids, Lubricants, and Genuine Parts" in
"Maintaining Your Vehicle" for further information.
MAINTAINING YOUR VEHICLE 781
NOTE: The presence of water in the gear lubricant will
result in corrosion and possible failure of differential
components. Operation of the vehicle in water, as may be
encountered in some off-highway types of service, will
require draining and refilling the axle to avoid damage.
Limited-Slip Differentials
1500 Model rear axles equipped with a Limited Slip
Differential require that 5 oz. (148 ml) MOPAR® Limited
Slip Additive be added to the gear lubricant. Refer to
"Fluids, Lubricants, and Genuine Parts" in "Maintaining
Your Vehicle" for further information. The MOPAR®
Limited Slip Additive should be added to the gear
lubricant whenever a fluid change is made to an axle
equipped with a Limited Slip Differential.
2500/3500 Model axles DO NOT REQUIRE any limited
slip oil additive (friction modifiers).
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