Having just recently aquired my first Oliver I have a few questions.  The light switch is broke off...i have a seperate igniton key on the left side of the dash thats just an On/off...is the light switch and ign supposed to be all in one on this tractor?  if so someone probably drilled a hole and put this switch in there.

also, what fluid do i put in the hydraulic system, i hear a very slight whine when it's idling almost like the pump might be a hair low so i wanted to check it and add if needed but was wondering what to use.

and finally for right now, i was told my hydrlectric is series 3..i can only find new harnesses for series 1 and 2..does someone make them for series 3?  or does anyone have one they would sell?
thanks for all the help guys