Cone style suregrip synthetic gear lube.

Well, I'll throw my hat into the ring.
I run Amsoil 75-90 with 2 bottles of Ford friction modifier in mine.
It is a '69 489 case cone sure grip.
I haven't had any issues with noises or chattering for 5 years now, so I'll call it good.
I had the same gear lube combination in my old '69 Super Bee that I installed a '68 3:54 Dana 60 in it that had the clutch sure grip and had zero problems with it, and I drove that car for years that way.
Also, I am a firm believer in doing the 20 or so figure 8s in a parking lot to work the lube into the clutches and or cone.

If you are doubtful on anything, then my suggestion is to follow what the F.S.M. for the year of diff you are working on recommends and you will never go wrong with that, or the gear supplier for that matter......