trans and transfer case fluid

[harleyhouser]

I have been replacing all my fluids(rear end, front end, motor) with Royal Purple. My question is what weight of fluid goes in the 4 speed standard transmission and what weight goes in the transfer case. Also about how much fluid in each?
The parts stores around here dont have any idea.
1971 Blazer 4x4 350 4-speed

Also does anyone know where I can get a dust cover for this transmission? I posted in the want to buy with no response. I have been unable to locate one.

Thanks

[Firebirdjones]

90 wt gear oil for both.