I vote for guide rod bushings. My car makes a clunk that I can feel in the lower driver's floorboard when I come to a stop, go over uneven terrain or turn the wheel quickly. I have done the test and I the guide rod busing is hot. The boot is torn and I can see the rust, etc. I need to fix this sooner than later. The parts are not very expensive and it seems like a DIY job. I just need the time.

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1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge