In case you decide to go for an engine, there's one in IL.
It is an '85 and looks like an engine I would buy if I needed one because the seller has listed COMPRESSION DATA!
http://cgi.ebay.com/ebaymotors/1985-Mercedes-Benz-300D-Turbo-Engine-Complete_W0QQitemZ8030979968QQcategoryZ33615QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!