I've rebuilt alternators B4 but not these ones, I must admit. I did a sealed one on the Eldorado I had but it did not have the fluid connections. I guess I'll have to wait till mine breaks and learn the hard way..
Good - Fast - Cheap: Pick any two.
E23 735i; E32 735iL (X 2 - 1 Alpine White and 1 Glacier Blue); E34 535i; E38 735iL; R50 Cooper; R55 Cooper Clubman.
E21 318i; E30 318i; E32 735iL; E34 535i; E38 730iL; E53 4.4i