There are unfortunately no markings on the arm whatsoever. I believe it was either made by HAPCO or GE though. GE hasn't made mast arms in YEARS though (decades really). I know currently the utility company uses HAPCO products.
Thanks! Yeah I had a 24" NEMA mounting arm (had the thru-bolt flange) but thought a 6ft arm would look cooler (which it does lol). The NEMA arm is an aluminum AE arm. Has the "ae" logo engraved on the lag bolt flange.