Hello TomBeck & Chief38:

Thank you very much for the information. If the biggest fitting problem is the notch for the safety - that's no problem at all. Had it on once, I think. And that was probably just to see what it did!

Edit: FYI, just got off the phone with S&W again and must have finally asked the right question. Was told the only visible differences between the old & new slides were: old has rolled marks, new has laser etched marks; old has a notch for the tab on the top of its safety, new has no notch for safety's tab (and all that needs to be done is remove the tab from the top of the old safety). Sound like a piece of cake to this kitchen table gun plumber!

Best Regards