What's the legality on this. Like if I used a song in a screenplay how'd I sell it.

The way I see it, you're basically suggesting a song for the production company that buys your script to use.   They'll have to deal with the legality when the time comes.

This is assuming that the song is just a simple choice for a scene and not an integral part of the story that people talk about, the plot revolves around, etc.  If that's the case, it could be trouble if, down the line, they can't get the rights to it.


EDIT:  I tried to get the rights to use 30 seconds of "Any Way you Want it" by Journey for a short of mine, and it was a complete shit-storm.

Yeah I think I'm going to take the scene out.

The film needs a massive rewrite anyway.