The AL27x and AL33x are genuine Bosch rebuild replacement numbers. The
original difference between the 2 types that came on waterboxers had to
do with the connector for the small blue wire. Either type works on all
waterboxers but you might have to change the end on the blue wire to
match. The earlier model had a spade connector and the later had a small
stud/nut to attach the blue wire. I have seen both types labeled AL33x
so somewhere the distinction may have been dropped or someone messed up
at the factory. The AL33x is supposed to have a "W" lead but not all of
them do including a NOS one I have on the shelf.  The latest AL33x
units I have seen had the "W" lead and thus are the most universal of
the replacements since they would work on diesels. Diesels use the "W"
lead for engine rpm data for the tachometer and/or upshift indicator.
Gasoline models don't care if the "W" lead is present or not.

Mark

TC wrote:

>>The 026 903 015B is the same as the AL27X.  The AL27X is specified for the
>>'83-85 Vanagon as well as most mid to late '80s Golf, Jetta, Quantum,
>>Rabbit, Scirocco and Audi 4000 & 5000.
>>
>>The AL33X is part number is 026 903 017B and also fits most of the cars
>>listed above, and more.
>>
>>
>OK I just check my 85 1.9L it has the following number
>259-903-023C whick I think is a Bosch AL27X
>But are you saying that AL27X and AL33x are interchangeable
>the only phyical difference I C is that the al-33X has an extra 'W'
>connector
>
>Determining What Alternator You Have
>
>
>