I have just picked up a 1939 torque tube and diff assembly , and trying to identify the stamped in numbers. If I look in the workshop manual it state that the number is prefixed with a the letter B for a Master deluxe with a 4.222 ratio, and the Master 85 is prefixed with a C or CB for the with a 3.73 ratio.
My problem arises in that the number is AA8243 and the main casting number is 593021 . The AA prefix doesn't match the Manual , is the AA a 1938 prefix ,as the chassis that this came from was an early production 1939 Ute with late 1938 date stamped chassis rails. ( my 1939 sedan has 1938 date stamped chassis rails also.)
It also has a letter D stamped in the casting on the top side of the carrier.
Is the AA a prefix for 1938 , and GM-Holden's continued to use 1938 assemblies until they were all gone.
