[Accelo]

All 4L60 and 4L46E are lockup transmissions.
Some electronic 4L60E can slip constantly with out damage.
GM uses this feature for a lot of things including keep speed in check going down hill while using cruise control.
On my Silverado the driver information system will tell me if the transmission overheats.
Their are plugins for your cell phone so you can read the temperature while traveling.
The Electronic transmission also automatically compensate for larger loads.
They measure every shift duration and adjust the line pressure to achieve a constant shift time.
I am a big fan of the Electronic transmissions.
Even the 87 to 92's are great transmission but with out the comfort and drive-ability features of the "E" transmissions.