Airline (Montgomery Ward) GSL-1079A Battery Pinout?

[Robert Grant]

I recently got a deal on an Airline GSL-1079A (a AC/DC/battery tube portable AM/shortwave radio, similar in circuitry to a Zenith Trans-Oceanic, only with two bands - AM BCB and general coverage 6-18 MC, eliminating the need for the huge coil tower) at a hamfest for $15.

I want to power it up with batteries to try it out. It uses 9V for the "A" and 90V for the "B" battery - just like a T/O.

The battery connector has three wires, which are black, green and red. The logical guess is that black is common-, green is 9V A+, and red is 90V B+. However, I don't want to leave that to chance.

Also, it does use the "unobtainium" 1L6 tube. I would like to try it out with a 1R5, which is known to be a "safe" sub on the AM BCB when one wants to try our a T/O. Would a 1R5 also be safe in the GSL-1079A?