Attached are pictures of the transmission, transfer case (PTO), and rear differential.
Make sure you take off the fill bolt first. (Highest bolt)
I believe the transmission bolts are 23mm. The drain plug on the transmission requires the use of a box wrench.
You'll want to change the crush gaskets for each of the bolts (plugs).
The part numbers are 99564-1800, and A601-17-117 (or 50501-000). These are cheap insurance, and should not be reused.
BTW, the crush gaskets for the oil pan is 99564-1400 ($1EA.) and should be changed with each oil change.
Redline is a popular brand, Motul, and Royal Purple are solid as well. Motul being the best.
MT90 -Transmission - 2.69 qt.
75W-90 -Transfer Case(PTO) - 1.3 qt.
75W-90 -Differential - 1.1 qt.
Rosenthal Arlington Mazda is a great place to order your parts. They have a 10 pack deal with oil filters that comes with the canister wrench! Fast shipping!
http://www.finishlineperformance.com/mazda6/maintenance.html