[L78steve]

Have you done any checking on the detent down-shift system?Check your switch for 12V supply with ign.on.Then activate switch and check for 12V output at the wire that runs to the drivers side of the trans.If you have 12V signal at the trans.you will need to check the solenoid inside pan.This can be done without removal of the pan.Disconnect the wire at the connector and check for continuity with an ohm meter.Hook one meter wire to the spade on trans connector and the other to ground (trans case).You should get a reading if solenoid is good.If it reads a zero resistance,suspect a shorted wire or solenoid.This detent should give you a full throttle down-shift up to about 70mph in 3rd gear.Or a second to first up to around 30mph.You may be able to hear a faint click at the pan when the detent switch is hand operated with ign.on if solenoid is functioning.