http://www.fordification.com/tech/M5R2_5spd-swap.htm
It mentions towards the bottom of the page that
The "2=2 wheel drive" part is incorrect. The transmission in question is actually the M5OD-r2. Mazda 5 speed with O/D. The R2 simply designates that it is the half ton version. It comes in both 2wd and 4x4 varieties. The M5OD-r1 would be the Mazda 5 speed with O/D from a Ranger-based vehicle.'M5R2' breaks down as:
M=Mazda
5=5-speed
R=rear wheel drive
2=2 wheel drive
Don't really know who I should have contacted on this, just thought the info out there, should be correct.
-Brandon