2low and manual lockup

I used a TC lockup switch in my 91 Chevy Suburban with 700r4 trans. Love using it. It was a simple thing to add to a 700r4 trans. Never could get one to work in a 93 4l80e trans. Its easier to do in non fully electronic transmissions. I have seen some for newer ones but are very expensive. Bow-Tie Overdrives has some for 4l80e's and Allison transmissions. I think Banks also has some for other transmissions.