ACA P-15 - Located at West Leyden High School. Taken 2/2021. Copyright Christopher Aylward
ACA P-15 - Located at the fire station on Parkview Dr and N Prater Ave.
HISTORY - The only sirens currently known which served Northlake before the P-15s and T-128 was an FS&S STL-10 which stood on a fire station next to an existing P-15. The fire station had a flag hanging from it which had 48 stars, which leaves a reasonable enough guess that it was a very old, possibly even Federal Enterprises, unit.
Historic Photos
FS&S / Federal Enterprises STL-10 - Siren was moved from the building to the tower at some point. Given the flag has 48 stars in one of the pictures, it's a reasonable guess that it's Federal Enterprises. A P-15 now stands less than 100 feet from it.