azdover,
I also did a another conversion. I picked up a really good 642 at a reasonable price. Just for fun, I swapped the converted 9mm cylinder from my 637 to the 642. I guess the machining of S&W is much better now as the two cylinders fit perfectly. I now have the 637 back as a .38 Special and the 642 is a "942." I had a 940 that I traded with another Forum member; while it was a good gun, it was too heavy (for me) for pocket carry. I guess I was spoiled by the Airweights having carried a 642 as a BUG while a LEO, and my converted 937. With the 942, I have the best of both worlds, 9mm and a lightweight hammerless revolver. I doubt I will ever swap the cylinders again, but it's good to know that I can.