Hey Dave,
I was always looking for an M5-R2, but I kept missing one that was only a mile away because the guy had it listed for sale as a ZF5. Once he realized his mistake, he relisted it and then I grabbed it right away. It was funny in the sense that it was for sale down the street for a month and I didn't even know;).
The M5-R2 does not have a PTO cover. It's pretty easy to identify though. It is a little smaller than the ZF5, and it has a long tail shaft like a typical transmission. It also has a slip yoke. Here's a picture of mine below:
The part number on the transmission data tag will tell you what speedo cable drive gear it has also.
Now I am no expert on the ZF5, but it is a bigger chunk of a transmission with a very square back end and a fixed yoke. Here's a picture I snagged from Google.
Nice work, Cory.