Just had my alt. rebuilt on my '87.  it was still working but while 
the engine is torn down, i thought i'd do a little preventative 
maint.  those of you that have tried to find or buy a new or rebuilt 
unit can appreciate the below prices.

bearing 303		$8.36
bearing 201		  5.46
tol. ring		  4.92
ABO 600S reg.	  12.98

Labor			  18.00

TOTAL		$51.78

The rebuilder, Terry, is a big beefy guy that loves to talk 
electrics.  Said it was critically important on these Bosch units to 
bring them in BEFORE a failure due to the cost of the housings.  If 
the bearings spin in the housing and ruin it, it is big $$ time.

-dan