true 600w oil

[Bruce Adams]

Many treat this 600W lube like its a sacred fluid.
WHERE is it noted as to be used in the Model A tranny, rear end, or steering in the Instruction Book or other period pieces?
I have found it, I think in one place in a Service Bulletin.
I use the mixture the vendors sell, and it seems to work.
Is there a frequency of bearing problems among those using different lubes?
Thanks for your help.