The 1303 was a radically different amp than the 1300, even though from the front they are nearly identical. The Lectrolab-built 1300s feature the amp-on-a-shelf design we saw in so many of the first Silvertone amps. The 1303 uses Danelectro innards, with Nathan Daniel's familiar two-part design; the controls and pre-amp on the top chassis, and the amplification and transformers located on a separate (usually bottom) location. This offers obvious options in control placement, and certainly some heat dissipation advantages as well.