Question about TSW number matching

[Lost Lake]

I've only got three pre-rail TSW's, having just finally found a pristine 4013TSW.

MY 4513 and 3913 don't have the numbered slide, barrel and frame. Was this something they started toward the end of the run of pre-rail models?

Obligatory photo:

 

[WTN1271]

Some good info in this thread.
http://smith-wessonforum.com/smith-...s/372715-lets-revisit-tsws-post137848476.html

 

[Lost Lake]

Thank you! That helps quite a bit. I guess I really need to get the S&W book also, especially if I'm collecting them, so I know what I am looking at. There are so many variations and little intricacies among all the guns produced, it is quite interesting!