There are a slew of reasons but my guess is bad power steering pump. Mostly because my Canadian R51 has a whiney pump. 3 hours is a long way on a guess though.
Depending on the mileage it still sounds like a pretty good deal, if that is the only issue. There obviously could be a lot more. The R51 is a great platform though IMO, especially the Canadian S models (All-mode 4x4, engine block heater, highest payload)