Got this link off TheSamba...
http://www.alltheprettybuses.com/_d_decoder.aspPretty cool. I decoded mine the old fashioned way a while back. My Camper was built in Feb '70, built to be an export model but was actually purchased in Germany @ the factory (then brought over to the US somewhere down the line most likely by someone in the military). It was originally a sunroof bus, painted beige with white top, then the camper options were added.
M-Plate is located behind your driver's seat on the partition...