625 smith,
You have acquired a nice 39. I would love to have an ISP 39 with the modified wide extractor. As you know the Illinois State Police was the first major Police Dept to adopt the 39 and as ISP Capt has stated, they worked closely with S&W to adapt the original extractor to the modified extractor on your pistol. If you listen to ISP Capt describe his pistols long usage you should be confident your pistol should work out just fine. I would NOT seek to replace that extractor with the original long extractor design. The mod was made to improve extractor reliability until a better design was introduced in the next generations of SMITH 9`S.
As Im sure you know, never manually operate the slide to battery. Most extractor failures are traced to this. Ive always slingshoted or dropped slide from lock back with the slide stop to initially charge. Just a reminder.
Good Luck with your 39
Im jealous.
Jim