The 444S stood for sporter model, the 444SS was the sporter safety model.
Got it, thanks for the clarification. That prompted me to do some more research and I found this on the Cast Boolits website.
Model: Marlin 444
Years made: 1965-71
Serial Numbers (first 2 digits): AA, AB, AC, AD, and 69 through 71
Barrel Length: 24"
Barrel Rifling: Micro-Groove, 12 lands
Barrel Twist: 1/38
1971: Mar-Shield finish and vented recoil pad appear.
Model: Marlin 444S - Sporter
Years made: 1972-83
Serial Numbers (first 2 digits): 27 descending through 17
Barrel Length: 22"
Barrel Rifling: Micro-Groove, 12 lands
Barrel Twist: 1/38
Notes:
1976: Forearm cap replaces barrel band.
1978: Honed chamber
Model: Marlin 444 SS
Years made: 1984-98
Serial Numbers (first 2 digits): 16 descending through 00 (2000). Year 2001 starts 99 descending.
Barrel Length: 22"
Barrel Rifling: Micro-Groove, 12 lands
Barrel Twist: 1/38
Note: The side safety appeared with this model change.
Model: Marlin 444 SS
Years made: 1999-2002
Serial Numbers (first 2 digits): 01, 00, 99, & 98
Barrel Length: 22"
Barrel Rifling: Ballard, 6 lands
Barrel Twist: 1/20
