Eurovan parts, but Vanagon related.

I most likely have to replace my ECU/ECM after my engine fire.  My ECU part
number is 023 906 023.  I see an ECU on ebay with the part number 023 906
023C.  How compatible is this to mine?  What about other ECUs with the same
numbers and a different letter?

Thanks.

-Dick Wong-
78 Scirocco
Original Owner
87 Syncro 2.5 (slightly crispy)
Third Owner
12 Golf TDI
Original Co-Owner