This post is possibly of limited use, but all of us watchgeeks and rephounds should find it interesting in the least. This information is by no means hard to come by, and I believe other before me have presented you the information, but here, upon those giants' shoulders, is a collation of all the pictures in an easy-to-digest format.
Where do replica movements come from?
I think it would be safe to say "Tianjin Seagull" in most cases. If you look at the TY-2846 version of the ST16, for instance, you'll see a familiar-looking GMT movement. The TY-2806 ST16 looks like that familiar Asian 21j.
Without any further ado, here's the stuff: Pugwash's Seagull Library
If any real experts, as opposed to a geek-with-google (me), wish to comment, I'd love to hear from you all on this subject.