The adapter for the Pro II D (XHX701) will actually work (with no modification) with an RZ Pro/Pro II with any Mamiya mount Leaf Aptus/Aptus-II/Credo digital back and any Phase One digital back P40+/65+ and newer (including IQ/IQ2). For Leaf Aptus/Aptus-II, you'd also need a $20 mini to sync cable, for Credo and Phase One, you'd need an 8 pin to sync cable ($58).
Now - the confusing part -
The standard RZ Adapter for Pro/Pro II is only available in the USA as a kit that includes an etched replacement ground glass, a motor drive cable that allows triggering from the keyboard, and the $20 mini to sync cable. This is part # 518-02210A (as Lance mentioned) for Mamiya 645 mount (also available in Hasselblad H and V mount). The cost for this kit is $1,430.
Previously, the stand alone RZ Pro II D Adapter could be purchased with no kit for $969 (roughly). This was part # 212-107. As stated above, on RZ Pro/Pro II, we have no problems making this work, with no modification.
However, in the current pricing from MAC, that part number no longer appears, instead there are Pro II D Interface Kits listed only for Credo, which list for the same price as the Pro/Pro II Kit ($1,430). However, to my knowledge, you cannot shoot from the keyboard with the Pro II D (ironically) and an Aptus/Aptus-II. We're not sure if that changes with Credo (we don't have a motor drive cable handy to try it, but we'll find out).
Assuming that is true, it doesn't make sense that the Pro II D Kit would cost the same as the Pro/Pro II Kit, since there shouldn't be a need for a motor cable, which costs in excess of $180.
So - today, if I have a Leaf Aptus or Credo digital back, and I don't need a replacement ground glass, or motor drive cable, I'm after a Pro II D Adapter, which is still in stock, part # 212-107.
That is, if you're not having luck finding one second hand, obviously.
We'll continue investigating the situation with the Pro II D Adapter kits, and what is actually contained (whether keyboard triggering works or not on Credo).
FYI - if anyone has an RB or RX Pro/Pro II, and purchases a new Leaf digital back for that platform, CI will accept your RB/RZ body and swap it for a free Pro II D Adapter, with purchase of a Pro II D camera.