Recently traded a '73 T100R with a very tired bottom end for a '96 Thunderbird. REALLY like the T'bird, but rear shock/suspension is horrible on Michigan's "pavement motocross" roads. Drives your spine up into your shoulders; day's riding means hobbling around and painkillers for next couple of days. I have tried playing with ride height/pre-load adjustments with no real success and could find no specs in owners manual, factory Triumph service manual, (provided by former dealer mechanic), or any of the various forums. The dealer mechanic says he dimly recalls setting ride height on them when new, but can't remember details. On one of the forums there was a thread about swapping for a '93 through '95 Kawasaki ZX7 rear shock. Claimed advantages were; improved compression damping, smoother ride, huge cost saving over $$$$$! aftermarket replacements and Kaw. shock is rebuildable vs the OEM Triumph unit which is not. I'm thinking that improvements may be due to; 1), the Kaw is a much lighter bike, and 2), the intended rider and passenger of the Kaw. would be younger and thus lighter than an old fart like me and the Kaw spring rate and shock specs would reflect that. I am about 215lbs and occasionally carry passengers; my 90lb daughter and my wife, (whose weight we WILL NOT discuss here! she says). The claimed disadvantage to swapping for the Kaw unit are it is about 14mm longer which raises rear ride height and thus may affect steering. Anybody out there have any experience with this? Any other tips/suggestions? Any help will be greatly appreciated.