[Accelo]

GM changed the tail housing from a 4 bolt style to a 6 bolt style on the removable bell-housing 4L60E transmissions. That's why you can't retrofit the eariler tail shafts to the late transmission.
BTW, you need to retain the electronic sensor when using modern computer controls.
This allows the computer to read the vehicle speed and can use that along with throttle opening to determine the required shift points.
You can see the hole for the second electronic sensor, in one of the pictures, I included in the prior post. It's installed on the opposite side and has the hall effect sensor connected to the wiring harness. The WOT shift points can be programed for each gear i.e different rpm shifts for different gears. Darn cool what you can do with the controls.
The program also delays shifts when it's cold out for better drivability. If you drive hard or have a trailer the computer will compensate by upping the line pressure to keep the shift times consistent. Tricks that are impossible with a non-electronic transmission.
If I was using a motor that required an ECM I would also use the electronic transmission. When the tuner modified the ECM, on my truck, he also changed the shift points to 6000 rpm in second and third and 4800 into OD.
Works flawlessly.
Stand alone controllers, for 4l80's, are over $900. That's why you don't see many. If you have to run a ECM you most likely have the controller built in. Some GM vehicles require a ECM and a transmission controller. That's for another day.
Cheers.