In 58 (like all 57 to 60 F100s) the common axle is the Ford 9". But, if the truck had a limited slip, it would be a Dana. A quick way to check is to stand behind the rear bumper, and look under the truck. On the Ford 9" you will not see any bolt heads on the center part of the axle (there will be nuts on the front). The Dana will have bolt heads on the back.