This thread saved me from buying a block heater as I had one installed already. Just wanted to follow up and say the picture and information above does match with my 95 F-250 7.3L Powerstroke. My plug was tied up near the air box on the driver's side, had a little cap over the plug.
Thanks for taking the time to help other folks out!!
P.S. - These trucks are only getting older and harder to find information on, KEEP THE THREAD ALIVE!