Midnight Flyer is an interesting one because if you compare the 1976/77 live performances to the 1974 DKRC version, the only line up change is having Joe in for Bernie, yet both of the other guitarists play a different instrument to the one they did just a couple of years earlier. On DKRC, Bernie is playing the banjo, with Glenn on slide guitar and Don F playing acoustic; in the 76-77 tour versions, Don F has taken over the banjo after Bernie's departure and Joe has replaced Glenn on slide, with Glenn moving to the acoustic part.
EDIT: Just noticed tlr has addressed this very same point!
I think I also read that on the few occasions that Try And Love Again was played on the Hotel California tour in 1977, Don F played the song's electric guitar solo (which Glenn played on record) with Glenn on acoustic.
I've just thought of another one (although I'm not absolutely sure of it), in this case actually one which I believe Glenn played live originally but relinquished when the studio version was recorded - Good Day In Hell. I can't remember where (I think it was on here) but there's a concert recording from late 1973 where I seem to recall reading that he probably played the slide guitar on the early version of GDIH, which if he did play it then means he would have handed over slide duties to Don F when they recorded it for On The Border. In the pre-Don F era I think Glenn always played slide if it was required, it was more his musical territory than Bernie's.