This question has been discussed to some extent already, with the following informative comment by Chaim:

Bernie is playing rhythm in the left channel and Glenn in the right. In the middle there's a guitar playing riffs. Before this song there weren't, I think (I don't have the albums with me at the moment), that many guitar overdubs during verses and choruses in Eagles songs. There were pretty much the basic guitar parts that were probably recorded at the same time with the drums and the bass. But this song features a third guitar right from the beginning. That could suggest that it's Don Felder. On the other hand, the lead guitar in the middle (that is doing leads during verses and choruses) seems to lead straight to Glenn's part of the solo. And when I compare the solo sounds of Don and Glenn, Glenn's seems to be a lot closer to the sound that's been heard up until then. In fact Glenn's solo sound sounds exactly like the leads that have been heard earlier, to my ears. Also, after the "heaven knows it wasn't you who set me free" line we hear a lick that contains pinch harmonics. Glenn played pinched harmonics all the time in the early 70's. So MY guess would be that it's Glenn playing the "non-solo" leads before the actual solos. But I could easily be wrong. On the other hand, the lick that comes after the line "And we never even know we have the key" is, if I remember correctly, also in "Too many hands" (during the guitar duel at the end) and there I think it was played by Don. So who knows!
There are two lead guitars during the fadeout. The one that is panned more to the left sounds more like Don's part in the actual solo part and the guitar that is panned more to the right sounds more like Glenn's part in the actual solo. I think it's Don panned to the left and Glenn panned to the right during the fadeout. But again, I could be totally wrong!

Here's what I hear and what I'm not sure of:

1. The intro lead guitar is Bernie all the way -- just sounds like him. He's panned left for the whole song, and after the intro just plays rhythm. True?
2. GF guitar is panned right when he's playing rhythm, but then he disappears from the right when some guitar is playing fills and riffs in the center. Is that him and not Felder? If so, how do we know this? Any clues other than the ones Chaim listed?
3. In the solo after the second chorus, two guitar leads are intertwined, a dominant one and a high ethereal one. Everyone seems to agree these are GF and DF -- which is which, and how do we know?
4. At the end of the song there's a lead guitar panned pretty hard left and another pretty hard right. Who are these guys? And how do we know?
5. And here are some bonus observations, not guitar-related: DH's high hat is panned a little right, and his tom and snare a little left; crash cymbals appear on left and right, sometimes alternating; snare, I think, is on the left; and at the start of the song, DH's tom seems to slide slightly in its left pan.

This is definitely Eagles nerdity, but I'm using this song as a kind of training exercise for my ear and for putting together my own arrangement/mix.

Thanks.