I changed the serpentine belt on my truck today and noticed that lots of the parts on top (alt., auto tensioner, ac unit) are pretty oxidized. I just got this truck so I have no idea of its history. The oxidation makes it seem like it sat for a while, but the 140k miles shows the truck probably didn't. So...

I was wondering if there is a way for me to check if the engine is original. Are there numbers I can check anywhere to cross references something?

thanks,

 

Do some research, find the previous owner(s) and ask them.