No they are still available. They've been about $200 expensive the last 5 years.
Pelican Parts - European Automotive Parts and Accessories - Porsche • BMW • Mercedes • Volkswagen • Audi • Saab • Volvo • MINI

The cheapest I found was Hamburg Tech at $100 but not sure of the quality. I just as well go with OE stuff.

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1983 123.133 California
- GreaseCar Veg System

That is odd, I searched for it in the SDL listing for '86-'91, and it showed nothing available. I typed expansion tank in the search, and only the plug kit came up. Yes I too later found them on ebay for around $200 OUCH!

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All Diesel Fleet
1985 R107 300SLD TURBODIESEL
2005 E320 CDI (daily)

LOTS of parts for sale!


EGR block kit
http://www.peachparts.com/shopforum/diesel-discussion/355250-sale-egr-delete-block-off-plate-kit.html

1985 CA emissions 617 owners- You Need This!
Sanden style A/C Compressor Mounting Kit for your 616/ 617 For Sale + Install Inst.

Sanden Instalation Guide (post 11):
http://www.peachparts.com/shopforum/diesel-discussion/367883-sanden-retrofit-installation-guide.html