So just picked up a 83' E-250 conversion in excellent shape with only 21k on a rebuilt engine. This thing runs great and everything works except the dome lights above the bed in the back. The front ones work fine and I have replaced the bulbs, but still no back lights. Just wondering a good starting point for attacking this problem. Can provide pics if needed.

 

there are 2 things i would think of first.
1) take a simple test light to determine if you have a problem with the hot wire or the ground
2) since this is a conversion interior, look closely for any signs of the previous owner installing a separate switch for the rear light