Ya know you're soaking in it !, yep, remember it well.
I struggle to post pics on the forum, otherwise I would show you my "brew" for the spline re-lube. Basically this is my method-
1. Clean and dry both male and female parts thoroughly. Inspect, naturally, and assuming all is well, I proceed as follows.
2. Spray both parts (M & F) with Loctite Moly Paste 51050 (65% Moly Disulphide) available in 340 gram spray can. Allow to dry (very important), looks like grey primer when dry.
3. My brew - Molybond GA50 assembly paste (50% moly), mixed with Castrol Optipit grease (1000cst base oil with tacky additive, don't get it on your hands !), then add a liberal amount of powdered graphite and mix thoroughly (I use an icy pole stick)
Apply liberally to both splines then assemble. I check mine annually (about 10,000Km's) and it's always still there.
I think there is an American lube which is a mixture of Moly and Graphite, can't remember the name, sorry.