I have a 97 T-Bird. It has suddenly developed a shudder around 30-40 mph. The shutter is almost like you are hitting the wake-up ridges on the interstate, but without the noise, only the vibration. Only last for a second or so. I have decided it was in the transmission. It is not related to the gear, but seem to do it the most just about before the time it shifts in to overdrive. But, I sometimes get this shuttering in other gears, and at different speeds. I have took it to two transmission shops. The first said my clutches were bad, and I needed a overhaul at $ 1500 +. The second said my clutches may be bad, but most likely, I just need to change the fluid and add a friction modifier as the clutch have developed a glaze over them. Cost $ 130. And somewhere between $ 1400-$ 2000 if anything more serious. Any comments on this or other opinions ? My T-Bird has 67K miles on it, and I last changed the fluid at 30k -35k Miles. Thanks Bruce