Thanks for all the excellent advice. You're right, I don't know for sure that it takes an 8AP4. (Maybe it's a 7".) But I do know that a 10" won't fit, I tried one. I like the idea of using a Test CRT. I will try to find one.
You're also right that the set has no power supply. Evidently, this was on a separate chassis (probably using a vibrator). The set has a rather large gauge wire for 12V power that feeds the filaments. There is a connector for the remote power supply with 12V out and a single B+ line in. The B+ input goes directly to a filter cap rated at 300V, so I know B+ is less than or equal to 300V. I figure I'll be able to make a good guess at the B+ voltage after looking up a few of the tubes in my RCA manual. I have a Heathkit adjustable HV power supply to experiment with before I build a dedicated supply.
This project is going to be a real challenge with no documentation, and no guarantee that this set even worked when put into storage. (Also I don't have much experience with TVs, antique or otherwise.)
A fellow poster put some pictures of this set on Early Television Museum. I have also posted to Antique Radio.
http://www.earlytelevision.org/delco_car_tv.html
http://antiqueradios.com/forums/view...p?f=3&t=234225
Bob D.