I bought a 53 foot semi trailer for storage this summer . I work out of town so I did not see it until a month ago .It was missing a battery and buying it for storage ,i did not think it would run at all . I put a battery in it and it started rightaway . It is a Great dane and has a Thermo King refer unit on the front of it . I think the Motor was made by Mercedes . It has 4 cyindlers and looks identical to a motor that was pulled from a thermo king unit I seen on Ebay. Can anyone give me any information about it ? It has a lot of hours on it (20000) which is not uncommon for a refer unit I have been told by the farmers in the local coffee shop (there is knowthing they don't know a little something about) .

a picture is worth 1000 words

__________________
1984 300D

You might do an internet search for Thermo King and Thermo King parts. They may have some pics or diagrams that you can use to identify your unit.
Also is there a plate with the information about the unit stamped on it rivited onto the unit anywere?

__________________
84 300D, 82 Volvo 244Gl Diesel

This one?

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=190266079371

Maybe that waybomb fellow can help you -

http://www.peachparts.com/shopforum/showthread.php?p=1643087

whunter offered this -

http://www.west-4x4.demon.co.uk/om636/

Sixto
87 300D

Its likely a thermoking engine.