8flat,
That picture worked...nice truck!
You have a 6400 Series 2-ton...
If it were me, I'd drop a 350 in and call it a day, it's a simple swap since there's a 283 in it already. The 350 will do more than the truck can handle...if you overload the truck the 350 will still move it, the BIG problem will be stopping it! Fix the 2-speed rear and run it in low rear while loaded and switch to high gear for the empty run home. She will go 65 mph empty.
Mike B
