There were two versions of the Martin B-57, license built English Electric Canberra, built with extremely large wings for high altitude operation, the RB-57D and the RB-57F.
The main purpose of these airplanes was strategic reconnaisance in a similar role as the U-2.
Currently at the U. S. Air Force Museum, a two seat RB-57D is being assembled in the Kettering Cold War Gallery. As of this past weekend, the main components not yet installed on the airplane were its two P&WA J-57's. The standard Martin B-57 was equipped with 2 Curtiss-Wright J-65's, which were license built Bristol-Siddley Sapphires.
Here are a couple of links to pages with information on the RB-57D.