I did not see the gun, but a friend that works in a fine gun room called last week to ask if I knew of a sidelock SKB O/U. Guy was in there to sell two SKB's, said he bought them in Japan in the early '70's. One was a boxlock and similar to a 500, the other a sidelock "a tad nicer" than a 600. Paul had looked in all the source information, books and internet and couldn't find one. I'm comfortable in saying Paul can tell the difference between a side lock and a side plate gun. No deal was done, but I told him, should the guy come back, I'll step forward and buy it. Always wanted just one gun NO ONE ever heard of!
Steve