All of the 2WD out put shafts I have seen on a 4L80E , they are all bolt on style shafts.
The 4x4 shafts are different.
The E brake tail housing design of the 4L80E will require the whole tail housing , brake and yoke.. these parts are all application specific.
This brake assembly is quite large diameter and may not easily fit under the floor of most cars.
Some people are like Slinkies... Not really good for anything, but they still bring a smile to your face when you push them down a flight of stairs.