Do All 4l80-e MT1 trannys fit into fbodys?
 

Do 4l80e's vary at all as far as tailhousings etc..?
Will they fit in fbodys if they are to a 6.0L stock?

You should be able to find pretty much all the info you want at this link.
https://ls1tech.com/forums/automatic-transmission/699277-whats-needed-4l60e-4l80e-swap.html