Answer to the first question:
A letter character following the part number could mean either an improved
version of the part (as a replacement) OR it could mean a radically
different part altogether and would not fit the originally designed
application - it may even fit a completely different model of the Volkswagen
product line. BTDT.

Answer to the second question:
Of the three different filler tube seals, only two are still available, 251
201 139 & 251 201 139 A.  The 251 201 139 B was dropped late by VAG last
year.

Answer to the third question:
Usually VW will indicate in the fiche or ETKA if additional parts are
required if the redesigned part requires it.  If the item in question has a
complicated replacement procedure, the fiche/ETKA will refer to a Parts or
Tech Bulletin number to accomplish the task.  The Bulletins are not on the
fiche?ETKA and usually in a notebook to kept on file at the dealership.

Answer to the fourth question:
See my previous posting to Jeff
--
Jim Thompson
84 Westfalia 2.1 "Ole Putt"
73 K Ghia Coupe "Denise"
72 411 Station Wagon "Pug"
oldvolkshome@gmail.com
http://www.oldvolkshome.com
**********************************
On 10/9/06, Jonathan Farrugia <jfarrugi@umich.edu> wrote:
>
> just for clarification you are saying that the parts are improved
> versions and physically different, not that the letter after the part
> number does not indicate an improved or redesigned version right?
>
> so on these three different filler tubes are all three still available
> from the dealer?  if only one version is stocked by vw does etka tell you
> all the other additional parts you need to make it work in an earlier van?
>
> any ideas on the differences in the ecu numbers that the original poster
> posted?
>
> jonathan
>
> On Mon, 9 Oct 2006, Mark Drillock wrote:
>
> > There are lots of examples where this is not the case. VW parts with
> > only a different letter suffix may not be at all compatible or
> > interchangeable, even if only one letter off.
> >
> > A Vanagon gas tank seal for filler tube comes to mind. There are 3
> > listed for 2wd.
> >
> > 251 201 139
> > 251 201 139A
> > 251 201 139B
> >
> > Good luck replacing any of the 3 with either of the other 2.
> >
> > Mark
> >
> > Jonathan Farrugia wrote:
> >> when vw improves or modifies the original part they add a letter to the
> >> end starting with A and working up for every revision.  all of the
> parts
> >> should work reasonably the same.
> >>
> >> jonathan
> >>
> >> On Sun, 8 Oct 2006, Jeff Oxroad wrote:
> >>
> >>> Here's one for you in the advanced class.
> >>>
> >>> Half price at the Pick and Pull today in Sunland,CA (near LA). Only
> one
> >>> Vanagon passenger Van. I grabbed an ECU off the 84. The part number on
> >>> it is
> >>> 025-906-021C.
> >>>
> >>> ETKA list the ECU for my 83.5 as 025-906-021.