I don’t think MTH ever made Premier A unit dummys, only powered.
Pete
Well, recently I was hunting around for a Premier E8 dummy B unit (UP livery) and found it, and in the process came across a few MTH Premier dummy A units. The one I remember is pretty recent as in 2019: https://mthtrains.com/20-21049-4. It was advertised as "non-powered" and sold as a single unit.
What I did for the B unit was put in a standing search on fleaBay and it eventually came up. (For some reason, Lionel has never made an E8 B unit and has mostly stuck with E7s.) You might look at the MTH online catalog and search accordingly.