The part is connected by two very short hoses to the expansion (not the
overflow tank) it is only on the 1.9 litre engines. If you look at the link
shown  below it is part #19 referred to as the Double Tee fitting

http://busdepot.com/water19N.htm

If you see any fittings I'd be eternally grateful + I'd buy one and pay for
shipping. Mine has what looks like a hairline crack down the skinny
interconnecting part that lets an amaxing amount of water blow out.
The VW part number is 025 121 438 and there is no B after the number which
indicates that it is for a later model van.

Thanks again

Tony