Transfer case PTOs will turn different directions and speeds depending on what gear you are in, not good for most applications. Transmission ptos only turn one direction the speed is only changed by rpm. Shifting the pto from one side to the other of the transmission will change the direction of rotation. PTOs are pretty much standard, either 6 bolt or 8 bolt. You order the direction of rotation and speed for the side of the trans that you want to use. They basically bolt right up though you must use shims between the trans and PTO unit to adjust the gear lash. I would rate a pto install as easier than a pyro, hard part is routing the control cable if you use that type of engagement. They can also be engaged by electrical solenoid or vacuum, much like the 4wd is engaged in our trucks, both are more expensive than the cable system though.