Thanks to everyone who took a look at this.
The concensus looks to be:
MODIFIED FOR OPERATIONAL
FLIGHT TRAINING PB4-Y
DO NOT INSTALL
IN AIRPLANE
We do know that the PB4-Y used the RAX / ART-13
in the Laision role, so this would made sense.
Thanks again!
73 Dave AB5S
p.s. No, I'm not planning to bid.
Already have them in the que.