That is not true. Both Federals and Darleys were stamped with this type up until about 1960/1970. The "TT" stood for two-tone. Federal changed it in the around the 1970's to just one "T". Also the Darley rebrands were extremely rare. Darley purchased siren parts from Federal, Sterling, and ACA and made their own sirens out of it with their own tags. Although some of the time they were just copies with different shrouds, they changed the port ratio on most models to 8 and changed the shroud and the tags too.nvanw27 wrote: ↑Wed Jan 06, 2021 6:09 pmYou can remove the 5TT/7TT and the WS-2500. 5TT/7TT is a Federal Signal Model 5T/7T Re-badged with a new housing by Darley, and the 2 "T"s are likely either a stamping issue or it was Darley's model of an existent siren.
The Whelen WS-2500 was never produced.
Also, there was reported to be some WS-2500's purchased by a power plant.
EDIT: IIRC, they stopped putting 2 Ts at the end around 1975.