I know this is an old thread; but, my Jeep now has the torque converter shudder when clutch is trying to lock up under 40 mph. I have an 2008 JK Rubi 4 door w/ auto trans and 109k miles. My mechanic suggested some Lube Locker "red" to help resolve the shudder. I'll try to remember to report back if that helped resolve shudder.
One foot in the grave & one foot on the gas pedal!!