GMC first offered Hydramatics in '53. Chevy followed suit in '54. And although they are not common, they aren't "rare".
GMC first
offered the Hyrda-Matic in PM series trucks in '52. I actually have a copy of the letter making the announcement to dealers. It was in the back of a GMC Master Parts Book I got a few years ago. I think those trucks would qualify for rare.
I have a '54 GMC with a Hydra-Matic and a buddy has a '54 Chevy with a Hydra-Matic and some of the parts on mine came from a '54 another guy was parting out.
While pickups with the automatic are not common they are out there.
