I've been going through my 61 Series IIA and finding that a lot of stuff I paid a shop to do was ignored. So I'm going to do a full service of the fluids. I use Amsoil gear oil in my Defender diffs so I might go that way. What do you all like for the t-case? How often do you change the fluids? I'm going to go with LR one shot grease for the swivel balls. Any advise suggestions would be greatly appreciated.