how to tell if engine's been swapped?

[wakingtowinter]

so I'm looking at buying this truck:

http://corvallis.craigslist.org/cto/1678416330.html

I talked to the guy and he said the truck has 250k on it, but the previous owner dropped in a new (reman, rebuilt, junkyard, i don't know) 4.0 at about 175k. But he has no paperwork to prove this. I don't have any reason to disbelieve him, but what can I look at on the truck to verify that this is not the original motor?

and also what on the tranny might indicate it's been swapped? thanks!

 

[BRUTUS_T_HOG]

take a look at the mounting bolts on the engine mounts and the transmission bolts and see how clean they are or if they are deformed a little. also look at the wiring harness.. if everything is out of place and doesn't look like its in its holders and stuff then its most likely been swapped