DId you say auto with no OD? That isnt right at all. They ALL had OD if they were intercooled.
At 60mph, if it has a stock Torque convertor, you will see anywhere from 1900-2200rpm, depending on the condition of the transmission. Same if you are in 3rd.
I'd look for typical stuff in a 93 truck of any make- front suspension, brakes, rear diff, odd noises, pulling when driving or stopping, u-jopints, interior, wiring nightmares. With that low a mileage, expect to do fuel system and brake system work on it- it has done a LOT of sitting, or a LOT of stop and go driving, neither of which are good for it.
Daniel