Signal Heads type question

[XamotCGC]

What kind of signal heads are these and how long they've been around in the enclosed google maps links?  The backs of the signal heads look different in each link.

https://www.google.com/maps/@37.5697812,-85.2528006,3a,25.8y,44.96h,98.04t/data=!3m6!1e1!3m4!1sV2XPKthWqrw5Glbq_mG_Fg!2e0!7i13312!8i6656

https://www.google.com/maps/@37.6853229,-85.2222909,3a,15y,103.34h,99.61t/data=!3m6!1e1!3m4!1sxMhejbqusSxJSYOWkuf3Ow!2e0!7i13312!8i6656