A lot would depend on the type of truck its in and what sort of gearing its got. They put those in a few 'regular' pickups but most of them tended to be in larger trucks and buses. Often times they would be geared fairly low for running around a city or out in the farm fields so they were never really intended to run for extended periods on the highway so they would likely be pretty terrible on the highway. I had an old small dump truck with a 305 v8 in it that would get me about 6 at 55 on the highway. If I tried to go 70 it did about 3. Just was not meant to be on the highway. Some of those trucks if they were going to spend time on the highway would have been ordered with lower gearing but I think those usually were 4 speeds with a 'granny' gear. A two speed rear end was a somewhat common option that way you could do city or highway.