It is a 9 and 1/4 axle. Ratio will vary between 3.55 and 3.92
Synthetic 75w140
Front is a 9.25 inch from American Axle Rear is a 10.5 inch from American Axle.
The 1500 4X4 went to the independent front axle in 2002. The 2500 and 3500 4X4's still have a solid front axle.
on the top of the rear axle
My 2001 durango slt plus 4x4 has 9.25 rear axle and 8.25 front
The speedometer signal comes from the abs computer via the rear axle speed sensor.
The 1500 has a Dana 44 The 2500 and 3500 has a Dana 60
1500, Dana 44 front, Chrysler 9.25 rear 2500 Dana 60 front, Dana 70 rear 3500 Dana 60 front, Dana 80 rear
Check for broken vacuum lines to the front axle shifter.
1 11/16 inch
75w90 with additive if limited slip.
Your rear axle is probably out. This would explain it moving in 4x4 because its utilizing the front axle.