Thanks for solving the mystery! I had the feeling the EHs must’ve dated back to the 1980s or something (the East Side Shaw’s Supermarket in Brockton, MA has those horns behind the SAE AV32 strobe plates as part of a Simplex 2001 system.)
Oh, and tpirman1982, you said “I guess some places prefer the older electric horns over newer, modern electronic horns.” Keep in mind that in the mid-to-late 1980s and the early 1990s, in addition to their 2DCD horns (rebranded Vibratone 450s), they also often used Wheelock’s horns with the AV32 light/strobe plates, usually either Wheelock 34/34Ts or those EHs.