While I am no expert (just another pion as the Mrs. says), any type of metal that is subjected to continuous load reversal is going to eventually wear out. The torsion bar is nothing but solid barstock that is twisted a small amount. After time, and who's LUV isn't older than 20 or so years, the "memory" that the steel has is going to being to fade. Kind of like us don't you think? Now where was I, oh yea, combine this with the enviornment the bars have been exposed to such as heat, cold, salt water, etc., of this begins to permiate the torsion bars as well as the rest of the vehicle and does take it's toll. Now I am not saying this IS what happens, but as I am in the air force and my carrer field is aircraft structural maintenance, I have to deal with problems similar to this on a daily basis. If you want to try other bars, give me about a month and I can send you mine for the cost of shipping (might be a bit high as they are heavy) since I am changing my front suspension to coil springs so the exhaust can be run through the chassis. By the way, I live in Las Vegas, Nevada.
Rick
1973 MG Midget
1979/80 Chevy LUV truck
acostahr@earthlink.net