It doesn't have any markings on it except for the hand written label shown. The casing is plastic and it has a professional looking nozzle. D = 24 mm, L = 70 mm. TIA.
I have some E6-4 and E6-8 motors also that look the same (also from 1984), I was thinking they might be Aerotech, but I wasn't sure if the company existed that early.