Your right Tom, it's a 6TPO. It's stamped in the side but barely legible.
The '67 just needed a recap. The '66 was recapped many years ago, apparently by me according to the owner when he picked up the '67, but now it's dead other than a thump on turn on.
I injected a finger pulse into the final, and it's loud and clear. One of the IF transistors has no voltage on any pin, so it's got a bad encapsulated module as it has very few discrete components on the board.
The closest manual I had is an AR-43 for a Galaxie, but the board in that has no encapsulated modules. The only thing they share is a PNP Germanium output. Glad I don't need one of those.
A friend thinks he might have the AR-36 so I'll find out tomorrow.