98 mustang

I have a 98 mustang 3.8 v6 with an aod and the transmission has a vibration when I am at 43mph-47mph. A friend of mine hooked it up to a computer readout of the systems and found the speed sensor speed read out different than the speedometor 5mph behind to be exact and it would act erratic jump speeds on the readout. Would that effect the lockout of the transmission and cause a vibration, if the speed sensor isnt the same speed as the speedometor. I am confused...could it be the speed sensor or a bad tourque converter???


Thanks JB

This is very commom in Ford Tranny's. It is called shudder, flush out the tranny (not change it) Flush it and it will be fine.