Corrected?
All I remember pretty much jibes with what you posted.
I dont remember a lot, but I worked at a shop a long time ago that had been a Motorola dealer. After the switch, the owner sold Matsushita Quasar for a short period of time, then switched to Zenith. It was already Zenith when I was there. Gobs of Quasar stuff still came in for service.
I used to own a works-in the-drawer (Motorola) quasar ll. I had the original receipt, it had been sold in 1974.
I remember seeing only two of the "changeover" models. I actually looked at the date on one because I was myself wondering myself exactly when it had been. I think it said 1976 or 77. These sets had the same (or almost the same) metal stampings for the drawer slide, but all the stuff on front was different, so it didnt look the same when closed. The boards and other parts didnt look anything like Motorola. and the sets didnt say Motorola on them anywhere.
I also remember seeing a Matsushita Quasar portable from just after the changeover was complete. A JCPenney set was sitting on the bench next to it. They used the same Matsushita modules.
All the best
John