[cotbu]

Lift the rear tires off the ground, put trans in neutral.
Test 1 Spin drivers wheel, look at the direction the passenger wheel spins.
Test 2, have someone hold the passengers wheel while you spin the drivers wheel.
Test 3, remove diff and look inside.
You could also spin the drive shaft and look at the direction the wheels spin.

The drive wheel is the driver side usdm, iirc
That wheel should be in the grass, mud or snow for the dump test. If not try both wheels.

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