A new or rebuilt alternator?
I did have my alternator rebuilt. It had been completely rebuilt twice, I was pointing out the failed component as the positive diodes. After pricing a "new" one from the dealer and seeing that even those are rebuilt for $600+, I decided to have mine rebuilt.

__________________
72 E3 Bavaria 3.0 4 spd-sold
76 2002 4 spd project
85 E24 635CSi 5 spd-son's
86 E28 535i 5 spd-sold
88 E28 535i 5 spd-son's
91 E34 525i 5 spd-sold
92 E34 525i 5 spd-sold
95 E34 525i 5 spd-sold
99 E39 540i 6 spd-son's
01 E46 325i 5 spd
01 E46 325Xi 5 spd
01 E53 X5 3.0 5 spd
02 E53 X5 4.4 AT
06 E90 330i 6MT
07 E86 Z4 3.0si coupe