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.