4l80e compatibility with 4.8/5.3

[FAKKY]

So ..... if you have a 4.8/5.3 engine from a truck/van that came OEM with a 4l60e ......

Couple it with a 4l80e from a different truck/van...

Does it all bolt right up - I read somewhere about having to get a custom convertor and/or spacer made with right bolt holes for flexplate ......but it didnt explain why. I know you need it if the engine is a "true" LS (LS1 example)
But unsure if not a true LS - like 4.8/5.3/6.0.


Also that the 4l60e and 4l80e same/different bolt pattern ?

etc