yes it is quite easy to add in the hydraulics and pto, also remember to get the shifter with thydraulic unit since the sticks are designed a little different between them. also the hydraulics and pto can come from any oliver from the fleetline to the three digit. i am not 100% if 66 parts will work but i am sure they will. also since you don't have the PTO there is a small shaft inside the housing that connects the engine to the transmission, the Pto shaft technically ran from the engine to the belt pully, hydraulics, and the PTO and i am not sure how hard it is to remove this shaft. also with the PTO i believe that you need a 77 shaft and clutch pack because i think they are a little shorter than an 88, but i am no expert and maybe wrong. i hope this helps you out hopefully an expert on the matter will respond.