SC 20 head (open) w/ L410H cabinet, miked in the studio for Teargarden
Kerry blogged on 2009/09/14 that "Billy is playing a 1961 Les Paul Junior Special through a Sound City Studio 20 amp, truly amazing sounding," although the accompanying photo showed a Gibson SG guitar. Additionally, a 50 Plus can be seen in the background of a shot of Billy from another of Kerry's blog posts on 2009/09/20.
Billy also mentioned on twitter that he had 2 Sound City amps, as a followup to a tweet on 2011/06/24, which included part of a list of 11-12 amp heads they were going through to prepare for the guitar tracking on Oceania. Exact models were not specified in his tweet.