The good news is that the differential contained the correct amount of oil. Maybe I should say oil and sludge. The Plymouth Instruction Book for the 29 U had no recommendations for cleaning this area but I felt after 78 years that maybe it was about time. The oil was black and had the consistency of molasses. The amount of sludge was incredible and needed to be spooned out of the bottom of the differential casing.
(http://www.chetscoins.com/1929/images/DriveTrain01.jpg)
For a blow by blow click on the link below...
http://www.chetscoins.com/1929/Work_Files/Drive_Train04252007.htm
Chet...