Okay, I've solved the problem. Seems like you guys were pretty evenly split on using dry graphite or a white lithium grease product. Since the MOPAR speedometer lubricant in the tube above looks like a grease product, that's what I went with. Pulled the upper cable. (Remember, this car has a factory cruise control setup. The lower cable (servo to trans) was fine, it was the upper cable (servo to speedometer) that was noisy). I removed the core from the housing, both of which were in fine shape even though they were salvaged from a 1979 Volare. I used brake cleaner to clean all the gunk out of the cable housing, and there was a lot in there. I then used brake cleaner to clean the old lubricant off the core. Again, there was a lot there. The old lubricant looked like amber colored grease. The brake cleaner took care of this stuff pretty quickly. I then lubed the entire length of the core with white lithium grease and worked it in and out of the housing to spread it around inside. I did notice that there was a significant amount of resistance when I spun the core by hand, so I withdrew the core and cleaned the excess grease off of it. It was now spinning freely so I put it all back into the car and it works like a champ. The ratcheting noise that it used to make is completely gone. What a relief! Just in case, I measured the upper cable before I reinstalled it, should it fail at some point in the future and I have to buy a new one. It was 36" long, for what its worth. Again, thanks for everyone's input. I've solved SO MANY Duster problems by talking to you guys and gals!
