For the most part PTO's are unique to one transmission only. The PTO gears need to line up with the trans gears and they are all different. The 6 and 8 mounting bolt patterns are all SAE standard making the PTO housings mounting flanges all the same...just the internal gears are different.
What you see as an Aux Transmission is more than likely the Main Shaft Transfer Case, it disconnects the rear axle and engages the High Volume Pump when shifted between the two functions (driving or pumping).
Mike B
