torque converter lockup. How much rpm change?

How much rpm change should you see when the torque converter is going in and out of lockup? I notice only about 100 rpms. If I tap the brakes, rpms jump up about 100 rpms, then come right back down. I'm trying to understand a little more about these transmissions. It seems to also have 6 gears... If you give it enough throttle to drop down,, it changes about 500, But if you bump it into 4th, it changes another 500. So, there is gear between 4th and D. But the only way to access it is under a little heavier throttle. I was always under the impression it just dropped from 5th to 4th.. But that doesn't seem to be the case. So is it a 5 speed with overdrive? that you cant actually access the 5th gear?

 

This sounds like a job for @gearcruncher

 

https://www.tacomaworld.com/threads...th-pics-for-second-gen-4-liter-trucks.289913/