Simple question

Ok, I know this is an extremely simple question, but neither the guy at my local napa, nor any of my repair manuals mention that info that I need. My original 55 repair manual has it, and ironically that is the only page I'm missing. What is the correct differential fluid for a factory 55 rear diff.? And what is the correct manual transmission fluid for a muncie M21? Thanks, I appreciate the help
-Cory

 

90w gear oil

 

90W gear oil for both the ****** and the rear?
-Cory

 

Gears is gears...yup!

ATF for juice boxes has a cleaner in it and is much thinner. It needs to keep the valve body clean for shifting.
90W is the thing for sticKs and rears.

Glenn

 

Thank you for the information!
-Cory