[Dead Parrot]

Does the rear end have some variation on limited slip/locking? Those sometimes recommend a special fluid or additive. On most rear ends, you fill until the fluid starts coming back out the fill hole on the side. Two one quart bottles usually leaves you with one bottle still having most of the fluid in it.

Start out with windshield cleaning fluid of the below 0* variety, assuming a Maine to Texas trip.

If the rear brakes are drum, do a few sharp stops while in reverse to adjust the rears.