the tranny in the chevy just had an external wire that led to the solenoid valve that locked and unlocked the torque converter.
The ford transmission has all its electronics inside the transmission and its controlled through one large harness that connects to the computer. The only way to disable the troque converter would to locate the wire responsible for working the torque converter in the wire harness and cutting it. Certainly a simple fix, but could take an entire day to locate the one wire in the harness.
I'm sure your mechanic would do it for you if you were willing to pay his labor rate for the ammount of time it would take to research the wiring schematics and then locate the wire in the harness. I could see 8 hours or $600 as a conservative estimate. Not worthwhile for something that will only cure the symptom and not the problem.
Again I suggest consulting a transmission shop that is familiar with Ford transmissions to get their opinion or maybe see if they can give you a free estimate to troubleshoot the problem.
