oooo sounds like the cummins might have rattled the guts outa the radio. . I`ve seen dodge radios go like this before, not necessarily in a CTD... All I can say is take off the dash faceplate, take out the 1/2" screws holding in the radio, and check your wiring, mainly check the ground strap. I`ve seen some come loose, and they can arc and cause this problem, but usually ending up in a fried radio. .
good time to upgrade!! heh (thats the first thing i did when i got my ctd)
-j