Anyone that doubts that the issues between Dave Mustaine and Metallica are well in the past should take note. Yesterday (Aug. 3), Mustaine sent public birthday greetings to lead singer James Hetfield, who turned 51.

The Megadeth frontman tweeted out the below picture of the two of them, along with the message, "Happy birthday to my first real guitar partner. We changed the world brother! #JamesHetfield"

Mustaine was a member of Metallica from 1981 to 1983, and was fired on the eve of the recording of their debut, 1983's 'Kill 'Em All,' due to his drinking and allegedly overly confrontational personality. Still, four of the songs he co-wrote with the band -- 'The Four Horsemen,' 'Jump in the Fire,' 'Phantom Lord' and 'Metal Militia' -- appear on the record, and two others winding up on their 1984 follow-up 'Ride the Lightning,' including the title track.

Clearly, the parties have mended fences since then, with Megadeth joining Metallica, Slayer and Anthrax on the 'Big Four' tour earlier this decade. In Dec. 2011, Mustaine joined Metallica during their 30th anniversary concerts at the Fillmore in San Francisco. He sat in on five songs, ’Hit The Lights,’ ‘Metal Militia,’ ‘Phantom Lord,’ ‘Jump In the Fire’ and ‘Seek And Destroy.’

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