Re: thinking of getting back into the Ranger game
From what i was told, both the 3.0 and 4.0 are good albeit the 3.0 isn't good on consumption/power ratio, they are both reliable.
Like any 4x4 make sure you check the transfer case and connected moving parts (drive shafts, etc).
I always preferred the manual to auto transmissions mainly because the person who abuses of it will most likely burn the clutch while an auto transmission will need a full transplant. Even with a "new" slightly used or rebuilt auto transmission, there is possibility of problems.
Best thing is to take it to a trusted garage, or dealership, for a full checkup.