Our 78 Mercedes 240D has over 500K on it and our  '81 300TD has 280K.
The '78 is our daily driver and we have found that the most expensive
replacement parts are body or interior parts that break. In my experience,
the engine parts are readily available at less expensive aftermarket
dealers, while interior and body parts seem to be only availalbe OEM or
salvage....and they are still pricey used.

    We have stalled in the process of re-istalling the 300td's engine after
it's rebuild because we were entertaining the idea of putting it in one of
our busses...interesting and timely thread!

Tracey Estevez
http://maritimeworkshop.tripod.com
85 Westy
78 Transporter
68 Campmobile
68 Beetle