Car-part.com doesn't recognize bigger trucks, and it apparently does not allow searches by engine size, either. Probably good for other parts.
I bought a good looking intact engine for $350.00 off craigslist. We pulled the pan, inspected everything we could see. This engine appears to never have been installed after it was rebuilt; sadly, I don't really know any more history than that. I am rather concerned about the health of an engine that was rebuilt but never installed. The skirts of the pistons looked fine, cylinders were good (what we could see), cam lobes were ok, the thrust bearing looked new, and the engine turned over nice and smooth.
So...we are going to see if it works. We must put our water pump on it, and we will trade out the ignition system and carb, since we know they are working.