Carquest Type FA when it was still made by Ashland. Don't even see it around even though Type FA fluid still shows up on the Valvoline site. Worked in the 2 and 3 speeds. Normally could still see the writing on the frictions after many runs. Wear was minimal over time when I measure the clutch plate thicknesses.

I tried Amsoil synthetic once. Made the high gear clutches streak black from slipping. Back to FA and it was good.

Have been told the Amsoil synthetic Type F is good. Never tried it as I changed fluid often enough that the cost would have been excessive.

I want the friction elements to lock up with a minimum of slippage. Not have a nice smooth shift so Grandma doesn't complain.

JD Hy-Gard is the current hot lick I believe. Especially in high horsepower applications. I've even heard of guys using shock oil. Maybe BS, maybe not.