Hi, I'm restoring an old DN that is mostly complete, but is missing one boom block. All the other pulleys are large, 4" x 5 1/2" with 1/8" thick side plates. The mount for the boom differs from the deck mount by it's concave mount surface v flat surface, but I could make either work I've been told this might be a Sarns block (?) If anyone has one laying around, I'd like to put it to use and keep the boat sort of period correct. Thanks, Paul