[Arran]

 I believe that they converted these pretty much as Terry suggested, even leaving the original rectifier and filter cap can. I've never owned one, though I would like to at some point, but from the photos I have seen they didn't have enough room on the chassis of the MoPar 801 to bolt an AC power transformer so they screwed a vertically mounted transformer inside the cabinet and extended the leads to connect to the car radio chassis. I believe that in the consoles that used a Ford car radio chassis they did have enough space to mount an AC power transformer on the chassis, or at least on the outside of it. 
Regards
Arran