<<GM did make a two speed based on the powerglide that needed to be manually shifted. The name of that unit escapes me but I'm sure it will come to me soon enough. It may have been called Torque Drive.>>
I rented a Chev once that had a goofy automatic called Turbo Glide. Maybe it was a Powerglide with a torque converter. Or sumpin'. I know there was a warning not to do something or other while driving it. So, I did it, but it didn't explode. RLE