It's at least at least a f600 or above due to the three ports in the rock guard . Also they were offered with a 534ci v8 .Here's a post I found on how's it work.com
1958 Ford F-Series
1958 Ford Trucks
Although the major 1958 news stories at Ford Motor Company were the introduction of the 1958 Ford trucks. Like their automotive counterparts, nearly all Ford trucks were restyled to accommodate quad headlights. But the big change -- literally -- was a new line of heavier-duty model trucks called Super Duty, which came equipped with new V-8 engines of up to a whopping 534 cubic inches.