We knew that when Green Day frontman Billie Joe Armstrong introduced Guns N’ Roses at their Rock and Roll Hall of Fame induction last April, the crowd booed at the mention of Axl Rose. We didn't know that Armstrong almost filled in for Rose during a retrofitted GNR set that night.

Duff McCagan, Guns N Roses' well-named and well-spoken bassist, spilled the dish on his Thursday column for Seattle Weekly. It's a lovely little story: When the boys from Green Day came by McCagan's book signing at the House of Blues, he and Billie Joe "devised a plan where he would sing whatever was needed ... if needed."

While seeing the 'American Idiot' crooning through 'Sweet Child of Mine' would have been awesome, Alter Bridge singer Myles Kennedy filled in for Axl Rose superbly, as did guitarist Gilby Clarke for Izzy Stradlin. McCagan praised "their heroic, last-minute efforts" -- the ad hoc band didn't rehearse until 2AM the day of the show.

Looking back on the show, which was taped as an HBO special, McCagan waxed reflective regarding how GNR fell apart while fellow inductees the Red Hot Chili Peppers and Beastie Boys stayed so much together:

... GNR didn't survive the folly and nonsense. We didn't rise above.
Watching that HBO Special made me sad -- for the very first time, perhaps--that the original GNR didn't somehow stay together. It would have been a miracle if we did. If I'd known then what I know now, I would have done my part to try and rid that band of the caustic resentments and outside inputs that finally wore us down to a nub of what we once were, and what we could have come back from. Alas, it just wasn't in the cards.

McCagan was satisfied with Cleveland, noting the Hall of Fame was about the music GNR made way back in the day. Still, in closing, he couldn't leave out a subtle barb toward Axl and Izzy: "The fact that a few of us showed up to reciprocate our appreciation was certainly enough for the occasion."

Here's a deal: How about Billie Joe Armstrong does vocals on the next GNR album?