The 60-series Toyota Land Cruiser was built from 1980 through 1990 and offered a combination of off-road prowess and comfort that was far superior to most of the competition. In the US market it was available with a thirsty inline-6 gasoline engine, but in some markets it could be optioned with a torquey diesel that matched the off-road character nicely. Find this 1987 Toyota Land Cruiser HJ60 offered for $14,500 near Phoenix, AZ.
With 190k on the odometer this thing has been around the block, but these cars are known for decent reliability and basic ruggedness. With a 5-speed transmission and a diesel engine (not sure if this is the 12H-T direct-injection turbodiesel, or the older 2H or 3B diesel) it won't be remotely quick, but it should climb hills with ease.
See another slow but fun classic? firstname.lastname@example.org