it would be easier to answer if you were more specific ....
for 1970 E-bodies, the rear sway bar did NOT exist until Trans Am/AAR production
prior to that S13 was front sway bar ONLY (STANDARD on BS-JS cars) & after A53, S13 included front and rear sway bars (the question might be: on what date did S13 ADD the rear sway bar to its contents list?)
ALL 440HP, 440+6, HEMI E-bodies had S15 included as part of the engine upgrade - front sway bar ONLY was part of S15 (ALL DANA60 cars have S15)
For my own brain clarity, was there an S15 and S13 as listed above or was that a typo?
If there was an S13 & S15 was the S13 front only and S15 both or ???
