Education needed on the difference in the Farmingdale and the Deer Park
RB,
About 7 miles.
Depending on the age of the two there may be nothing more than the engraving on the slide. A current production Deer Park has a few updates over an all original Farmingdale. I believe there was an extractor upgrade, slide upgrade (there were some cracking issues at one point) mags and springs upgraded.
I'm sure some of the resident experts will add to the list or correct it.
John