Well, honestly, the question you seek answers for is somewhat of a 'trick question'. Everyone has a different valuation on these things, some common-ish numbers floating around are in the $700 range for a good, rebuildable unit, or a runner.
That the engine only has 160,000 miles on it is kinda irrelevant as there is a difference in operation, if the truck has literally had the crap kicked out of it daily for every day of it's life, the engine is THRASHED and worth WAY LESS, but if it was a daily driver for a guy( or gal) that commuted 60 miles each way to work and the truck was well cared for, that engine is GOLDEN, and commands FAR MORE.