Just yesterday, I drove all the way out to Illinois and purchased this Thunderbolt siren from a friend of mine who is also a siren enthusiast (WindyCitySirens on youtube)! This is unit T4053-DR from Dimondale, MI, however it has a mismatched chopper and has a 1950's 1000 chopper instead. I'm glad to say I finally own one of these awesome sirens!
https://www.youtube.com/watch?v=mx-mezQ ... ofMichigan