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.
>>
>> .............