argh. that should read ...
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 here's what Bosch says about its alternators.

 Explanation of Type Codes
 In addition to the 10-digit Bosch part number (which for alternators,
always
 starts with 012...),
 a type code is stamped on all alternators. These codes can be interpreted
 with the help of the following example:

 Type Code Example:    K X () 14V 35A 20

 K - housing outer diamter:
       G = 100...109mm
       K = 120...139mm
       T = 170...199mm
       U = more than 200mm

 X - 1 = claw-pole alternator
       2 = single-pole alternator
       3 = generator with permeable rotor
       4 = claw-pole alternator with exciter

 () - (->) or R  =  clockwise
       (<-) or L  =  counterclockwise
       (<->) or RL = either direction
 (direction, as seen looking onto the driven side of the alternator (on
 models incorporating their own rotor bearings)).

 14V - alternator voltage in Volts.
     (the indicated alternator voltage (7v, 14v, 28v, etc) should not be
 confused with the nominal voltage. the indicated value, which appears on
the
 name plate, is the nominal working voltage. it is the approximate average
of
 the charging voltages required for various types of batteries and operating
 conditions. in contrast, the nominal voltage is the standard
battery-voltage
 (i.e., circuit voltage when alternator is NOT running). nominal voltage
 ratings (e.g., 6v, 12v, 24v, etc) are commonly used to identify starters
and
 electric accessories which are operated at this voltage.

 35A - maximum current in Amperes

 20 - speed (rev/min) in hundreds at 2/3 max. current (20 = 2000rpm)