Greetings and welcome to the forum. Here are pics of the SAS-3, SAS-2 and fast idle screws on two spare carbs I have for a truck with a manual trans and no A/C. The SAS-2 screw is in the middle.
Carb_1.JPGCarb_2.JPG
Like the other adjustment screws, the SAS-2 screws on the carbs I have use a spring to hold their position instead of a lock nut as illustrated below. Also, here's instructions for adjusting and setting the carb. The SAS-2 adjustment procedure is #4.
Adj_screws_illstn.jpgAdj_steps.jpg

Hope this helps