I think you thinking here is not right.

the first 3 #'s .........I think those are based on the first car the part
was used in, opr to major groups, like the 251 I mention below.
like 056 to me .......refers to Rabbit cars.

for example, a 1.6 diesel block with 11 mm head bolts, the parts number
starts with 056.
the 1.6 diesel block with 12 mm head bolts, starts with 068.
if it's a 1.9, I think it's 028.

body and chassis parts in Vanagons start with 251

if anything, the last 3 #'s refer to the exact part, like in your exhaust
vavle example, it would be the 612, and the suffix A is another version of
the original exhaust valve, like an updated part.

----- Original Message -----
From: "Jonce Fancher" <streetbugs@VERIZON.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Sunday, November 22, 2009 4:23 PM
Subject: Model designation Numbers all Model VWs

> Hi all
> Not sure if some one can send me to somewhere to find out what the
> Model Numbers for a part number are.
>
> Like a VW part number 025 109 612A. The 025 is Vanagon Exhaust Valve.
> Now if it is a 043 109 612A What VW is This Exhaust Valve for?
> Now if it is a 1H0 109 612A What VW is This Exhaust Valve for?
>
> Is there a Prefix showing ALL Prefixes?
> I've not been able to find one.
> I have parts with 022,025,026,027 and a ton of others.
> Any help would be great. Or just a link to all.
>
> Thanks. You can email me direct if you don't want to post this to the
> list.
> Thanks