Transmission and rear axle grease recommendation

[denverslim]

Hi Fellows,
So mine is a '66 C-20. I am wanting to change the fluids in the trannie and the rear end. Can someone tell me what is a good modern day available grease and viscosity to use? Capacities would be helpful also.
I know, I need to get a shop manual for this info but the forum is so easy.
I promise, I'll write it down for next time. Lol.

Probably should have included the transmission is the four speed.