When Merle and Joe were in town for the WPC I got to check out Merle's truck up close and personal. We dicussed the drip rail detail a bit as it was different than FEF's and Joe's. Well, now that I have a cab from both designs of the Pilot House trucks, I can say there are the following differences between then cab designs (please feel free to add if I miss anything).
1. drip rail: 48-50 it is more open almost "U" shaped, 51-53 it's curled back towatds the cab
2. wiper locations are different
3. dashes: with a note the 53' has a different dash badge than the 51-52 but the rest is the same