Pretty nice guns, have had more than a few over the years and they shoot well. Normal production for the Speed-Six were 2-3/4" and 4" barrels. A few Postal service (GS-33PS) & a few Immigration and Naturalization Service (GS-33P) Speed-Six 357 3" guns were made as Pete noted. If one of these with a 3" barrel it is more than a bargin @ $375.
Speed-Six = fixed sights with a round butt grip frame, 2-3/4", (rare 3"), 4".
Police Service-Six = fixed sights with square butt grip frame, 2-3/4', 4", 6".
Security-Six = Adjustable sights with square butt grip frame, 2-3/4", 4", 6".
My 4" 357 Speed-Six.
The second one down on the left, a police Service-Six, I think I still own it, but haven't seen it since my daughter
borrowed it some 5 years ago.