Well Rick, many things have high-priority right now.
We have already sliding adapters for V, for H, for Contax 645 and for Mamiya 645. Next to come is the Hy6 interface. I don't know what you precisely mean with "Will the Arctec and p3 use the same plate", but a back with Hy6 adapter plate will fit the Sinar Hy6 MF body, the Sinar arTec camera, and the p3 sliding adapter.
Best regards,
Thierry
Wow I'm just so surprised that it the case. I just would have thought it be a high priority. I mean Cambo have got one for their sliding back. Will the Arctec and p3 use the same plate?