While in the absence of any documentation I agree with the generic "application" recommendation, the manufacturer specifically recommends SAE30 oil for this application.
There are many types of trans-axle gears, the Graziano does not use the hypoid type gears that would benefit from the protection provided by the gear oils.
Sometime additives can be an issue as well as some are corrosive to yellow metals and while I don't know if any copper, brass, etc alloys are used in pins or seals in Graziano trans-axles, I personally would go by what the folks that designed the equipment recommend.
This is what I use:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1