025 906 021 is for Digijet 83.5-85 Vanagons.  The one marked "Digijet" is
the same thing as well.

Here's an excerpt of a post I made to the Vanagon List 10/9/2006 (Damn I luv
Google's mail search function!!):

 Quick data notes:

025 906 021 = Bosch 0280 000 501 or 502 - USA or CDN 1.9 83.5-85
  Note:  Bosch Rebuilt CU114X (No Longer Available)
025 906 021A = Bosch 0280 000 509 or 510 - Europe 1.9 83.5-85
025 906 021B = Bosch 0280 000 512 or 513 - Europe 1.9 83.5-85
025 906 021E = Bosch 0280 000 522 or 523 - Europe 2.1 w/Digijet 86-91
  Note:  I believe this is the ECU Boston Bob provides, but I really don't
know.

Sources:  Bosch Data Fiches, "OE to Bosch" and "Bosch to Where Used".
--
Jim Thompson
84 GL 1.9 "Gloria"
84 Westfalia 2.1 "Ole Putt" (w/2.1 Digijet ECU)
73 K Ghia Coupe "Denise"
72 411 Station Wagon "Pug"
oldvolkshome@gmail.com
http://www.oldvolkshome.com
***********************************
On 2/27/07, Nathaniel Poole <myth.wright@gmail.com> wrote:
>
> Hey all, I've got two ECUs here and I'm trying to figure which one is
> is which. I have one marked Digijet and another with bosch # 025 906
> 021. I Believe one is for an 84 1.9 and the other is for a 2.1. Can
> anyone help me with this?
>
> Thanks
>
> Nathaniel