My 85 f150 4 speed strait 6 4×4 how are they on prolonged trips 2 to 3 thousand miles? At 55 to 60 mph??
The 300 straight 6 is an incredibly durable motor. At constant speeds, any engine will do well. At the speeds you mention, you won't be stressing it at all. I've been coast- to-coast with an Econoline equipped with a 300 six, full of family and pulling a trailer. I got 200,000 miles on a rebuild - enjoy! (of course, proper maintenance is key!)
chain or direct gear to gear on 300-6 ?
Gear to gear - there is no timing chain.
In high gear and at 55 to 60 your engine's rpm will be slightly over twice that of idle speed. If the bed is not loaded down with stuff or pulling a trailer. You should have no problem. I'd change the oil prior to the trip if close to oil change time.
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