Id it is determined by clutch pressure than we know it is a transmission or clutch issue. If it is not doing it when the truck is in gear and moving, as you stated, I would say it sounds more internal transmission related than anything. There may be some sear alignment issues inside the transmission causing the thumping sound. This seems the most likely case, as the noise comes and goes. At 200,000 miles it wouldn't surprise me if the truck needed a maintenance overhaul on the transmission. I would get it checked out ASAP before more damage is caused.
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Sunday, March 13th, 2011 AT 1:35 AM