Well, I may have read your post a half a day too late as I purchased the tray, back plate and connector cables for $175.
True, I may have paid a bit more.... thanks for trying to help me
So, I think I now have ALL the components I need to help my buddy Cal to have a newish digital transponder so we can all see him (electronically) and so that he can get ADSB out in the future.
This is a gift to him for being such a good guy and always doing good things for others. I didn't want to wait too much longer!
Thanks to everyone for the assistance and advise! I'll let you know how this works out!