I have looked but

1wild&crazyguy said
the lower plug on the pass side drains it, the upper fills it.
66 right? thats the non syncro 3 spd.

you can fill it with 75-90w gear oil.

If I remember right it said in the book that second gear only is syncro.
How much or how do I tell if it is full, and yes 66 model 8)