No clue about when most of the individual model #'s changed (ditto for the portables), but here's what I think to be true about the stationary saws....Prior to Emerson, the Sears stationary saws were made by King-Seeley (1950's?). The 113.###### contractor saw series was made by Emerson in the USA from before I can remember until around 1997. After 1997 they went to the 315.###### series made by TTI/Ryobi until 2004 (pretty much the same design as the Emerson made saws, but made overseas).
Next up for Sears were the "zipcode" hybrid saws with cabinet mounted trunnions (22104, 22114, 22124) made by Steel City/Orion made until around 2007/2008.... the 22116 is the current hybrid (still made by SC/Orion) and replaced the 22124 when the riving knife requirements went into effect. The 21833 hybrid style contractor saw came along shortly after, and is also current.... made by Dayton AFAIK
(imported through Colovos to keep us guessing). (As a side note, both the Emerson saws and the TTI/Ryobi contractor saws lived on for several more years carrying the Ridgid banner, and those were replaced by a Steel City/Orion made hybrid saw (R4511), and then the R4512 hybrid style contractor saw made by Dayton.)
TTI/Ryobi still makes at least some of the portable jobsite saws and the Ryobi BT3100 clone (21829) for Sears, as well as their dreadful benchtop saws. The 21828 portable is the same as the Ridgid R4516.
Steel City Craftsman 22114:
Steel City RIdgid R4511:
Dayton Craftsman 21833:
Dayton Ridgid R4512: