Yes, trans oil and gear oil as a syn oil is required by the mfg."diff oil" Redline is the lowest priced syn oil I can find.I have used MTL with great results.
PS fluid (Aerostar)
ATF (Aerostar)
Gear lube (Motorhome I sold, but will use next time I change a diffy fluid)
motor oil (only in air cooled motorhome generator at this time)
Also have half dozen Redline fuel system treatments.