Anyone aware if torque converter lock up can be controlled manually similar to the 46RH toggle switch set up? I would like the ability to turn the lock up off when towing. TIA

Make sure you turn off the overdrive when towing. Why do you want to turn off the lock up? It will cause the fluid temp to go even higher. The pcm gives the lock up solenoid a ground to engage lock up, You can simply cut the connection and add a switch.

The lightest touch of the brake pedal will trigger the PCM to unlock the torque converter clutch.
I find this useful when approaching the crest of a hill and do not want to have the trans downshift to 3rd gear.

A momentary contact switch mounted to the floor on the left side for your left foot to lock the TCC can also be useful.

Most drivers don’t understand why 3.21 diff gears can be better for “realworld” towing as it allows for climbing hills in 2nd gear with TCC unlocked at acceptable MPH.

With 3.55/3.92/4.56 ratio 2nd gear is too slow.