What lube for a 39 top loader and how much

[Ziffer]

I'm wondering what you all are using for your early Ford Transmissions? There are seemingly limitless options out there for both the actual fluids and then fancy additives. I'm a firm believer in keeping things simple, but it some of these products are superior I'm willing to use them. Also, what do you use as a fluid level in your top loader trans.

Thanks
Z