If you don't have a copy of Bruce Anderson's
"Porsche 911 Performance Handbook", get it. In many of this website's tech forums, the responses for important, critical information may vary from incorrect to factual and opinions in-between. You might want better assurances for confirmation. BTW, S con rods are NLA.
Photos and description show the difference between 2,0-2.4 liter S and non-S con rods.
Anderson says S rods are beefier and nitrided (darker, black finish).
Porsche 911 Performance Handbook - Bruce Anderson - Google Books
Think for a minute. Porsche assigns the same part number on different parts, then uses non-permanent, hand-written white paint to further differentiate them.
Sherwood