So, I found this NRC document on accident and found out that the VC Summer Nuclear Plant in South Carolina formerly consisted of dual-toned ACA Banshees, dual-toned ACA P-10s, single-toned ACA Screamers, FS Thunderbolts, and two Whelen WS-2000 series sirens.
The evidence is on page 2 of the document (well, page 7 of the PDF file), where the older siren system is mentioned alongside the newer system. I made sure that the old system wasn't discussed here before by searching for key words, and it doesn't look like it has been discussed yet.

Here is the document:
www.nrc.gov/docs/ML1436/ML14363A376.pdf