Found this pair of AR-3's stored on a basement shelf at an estate sale earlier today. There were no grills and no labels on the rear and, hence, no serial #'s. At first I thought they may have been user modified, having a 3a woofer and midrange, so I pulled the woofer on one speaker to find matching dates on the woofer and tweeter, and a dual cap with 6 and 2 microfarads in the mid and tweeter circuits. Very interesting. I've never seen the 3a woofer in an AR-3.