I saw a compressor on it in the auction brochure. It must be air over hydraulic because the dive axle has hydraulic brakes. 60 mph with 9.00x20 tires will be 3400 rpm. These things were built to turn 3400 rpm all day long. 45 mph is only 2600 rpm. It is going to use a lot of gas whatever you do to it. At 60 mph the wind noise will probably drown out the fan and rocker noise any way. You need to remember this is a 60 year old truck.
