I have several movements sans watches and in my free time I service them (the more popular ones at least)  so I usually have one on hand for a quick swap. I've been working on a Seiko 6309 recently, an ebay special. This movement was marked '6349' on the auto-wind bridge but on removing this I was a bit disappointed to see that the third and fourth wheel pivots were unjeweled... this was the plain jane, vanilla 17 jewel 6309 with a 6349 autowind bridge thrown in!. Ah well, the 6309 is good