Exactly right. The fact that the first 9 numbers match means nothing as
far as interchangeability. Here is an example of 5 replacement part
numbers used on Vanagons built during the 85 calender year.

251 407 312 AE
251 407 312 AF
251 407 312 AG
251 407 312 AQ
251 407 312 AT

NONE of these parts are swappable as single items. Some can be used as
long as other major parts are swapped as well. Some can't swap at all.

Mark

Mike wrote:
>    Never assume that if the suffix letter is the only difference, that it must be okay to choose as a replacement part.  Any time a VW PN has a different suffix letter, that indicates that it's a variation of the part, and is designed for a specific application.  Generally, lower suffix letters are usually for earlier versions and higher letters are for later changes or other versions.  On occasion, it's a totally redesigned part and would never fit anything except what it's designed for.
>
> Mike B.
>   ----- Original Message -----
>   From: AD Felder
>   To: vanagon@GERRY.VANAGON.COM
>   Sent: Saturday, April 11, 2009 11:19 PM
>   Subject: radiators
>
>
>   Anyone know if there is any difference (other than the letter appendage) between radiator 068 121 253A for a diesel 82 and radiator 068 121 253E for watercooled 84-91? Can the more available E version be used to replace an A version in an 82 diesel? fasten points the same?
>
>   Appears I have a crack, lower right, rear face in the plastic near the return hose outlet.
>