Dating a Bigsby Vibrato

I wasn't too sure where to put this post, but since the Bigsby in question probably came from a Gibson, here it is.

Is it possible to date a Bigsby vibrato? I am pretty sure that this came off an early 1960s Gibson ES-345. It is gold plated, although most of the gold is long gone, except of course on the back.

- on the front of the tailpiece, it says "Bigsby Patent No. D-169, 120"
- stamped into the back of the tailpiece is "L P"
- also stamped on the back of the tail piece, although in somewhat crude letters, is "EX SHOOT" (this was not scratched or carved in later because it is still covered by gold plating.)

If there is any interest, I will get off my butt and post a few pics.