Don't know, makes no difference. Why the question?
If you need one order from S&W and it will come the correct length.
If you have replaced the extractor rod and are having unlatching problems because the center pin won't fully disengage the locking bolt, the solution is to shorten the extractor rod until the center pin does disengage the locking bolt from the end of the extractor rod.
Rather than shorten the extractor rod, I think I'll try to remove the stud that supports the front end of the extractor rod and reshape it. Now my question is, what size cup tipped punch do I need to remove the pin that holds the stud in place?
Dick
Does the center pin come to the end of the extractor rod when you fully depress it? If not, IHMO the correct solution is to remove the small amount of material on the rod to make it flush with the center pin. And if you did buy a new center pin, it is a part that needs to be fit to the revolver. I just can't imagine a case where modifying the locking bolt is the right answer.
Read my signature line! I have been doing this a whole lot of years. I already gave you the answer how to fix your problem.
Shorten the front of the extractor rod until the end of the center pin is flush with the extractor rod. To check this place the back end (extractor) against a flat surface to push the center pin flush with the extractor. If the extractor rod is even .001-.002 above the end of the center pin you will have problems opening the gun. Preferably face the extractor rod in a lathe, but filing will work fine if you can file the end of the rod so it is square.
That's twice. Now, do it right or do it your way, your choice.