Casey,

Thanks for the offer. I won't be doing the install until the March time frame so I might take you up on your kind offer.

Short of finding these adapters I could just (temporarily?) use some aluminum plate to make a transition piece from the rectangular hole pattern of the control head to the square hole pattern of the 56mm round instrument cutout. The head wouldn't be flush to the panel face but, aesthetics aside, it would work. And how often do I even LOOK at the transponder anyway?