Yes, I'm almost positive that Royal retracts are actually MK gear. I think MK may have cut kits for Royal (the MK and Royal Spirit of St Louis kits are identical)at least during the 'early' years until Marutaka did the kitting (I also wonder if Marutaka was a spinoff of MK - MK kitted several scale kits in the late '60s / early '70s then focused on pattern/aerobatic aricraft exclusively) . Actually, I believe the 'Royal' name is a US name and not the original manufacturer.
Great acquisition - you should be set for mechanical retracts for a while!!
-Will