Hi
You have a very nice S-120. The S series was replaced by IHC, mid 1957, with the A series. It is NOT an A! The A is a completely different body that takes a different windshield. Sometimes if a vehicle doesn't sell in the year it was built, it is titled in the year its sold, but that still doesnt make it an A. The rear box & fenders were carried over to the A's.
Someone has taken good care of it. It doesn't show too much sever use. It has numerous accessories that are niether stock, nor military. To my knowledge IHC never had a stock rear step bumper. They were all aftermarket, and therefore, there are numerous designs and shapes. It does have the holes for a pintle. The front bumper is a home job. It has some bows & a replacement tarp. The screws in the brass name plate, stating its an A, are not IHC. Certainly the cab and front fenders don't go with the Tag! Mostly it looks like somebody wanted it to look military. Different layers of paint would give some clues.
Its a very nice old truck. That little Dana front axel needs some new wipers on the ball joints, The front springs tend to loose their arch on those. That changes the castor some and they will get to shimming. Keeping the front tires balanced, helps, as does the shock on the tie rod. The hood was made to open from the side. It was probably geared low. There is often a tag on one of the bolts on the differential carrier housing, with two numbers on it. Divide them, to give the rear end ratio.
Thankyou for sharing your pictures and good luck getting a duece.