The B32 was my next guess, only reason didnt go with that, the 32 had an ungodly high vertical tail; the one in the pic doesnt look that high.
The B32 was a response to the same bomber requirement as the B29 (the Lockheed Constellation design was another), and was kept on as a backup in case the 29 couldn't overcome the challenges of its more radical design. Only one squadron saw combat, hitting Japan from Okinawa at the very end of the war.