Saw a movement listed as a 105.012-65 that has a symmetrical bridge. Serial seems right on the edge of -65 and -66. Symmetrical bridges didn't come on movements this late, though, did they?

 

Symmetrical bridges were not seen on any lyre lug Speedies

 

That's what I thought, thanks.

 

There is a so called transitional movement with a symmetrical bridge and stretched adjustment index, but actually only in the 105.012-63. So either the bridge was swapped or, more likely, someone chose to swap the serial bridge. To quote spacefruit: hurdles to do that are technically and moraly very low.