is there a serial or vin # on a 3rz engine?

I was just wondering if there was a way one could identify what year the engine is. Just wondering because my taco has a good 300k on the truck and I'm curious to see if its the original engine. There's a few little things like wire harnesses that appear out of place and the exhaust had been cut and welded back together just after the manifold that would lead one to believe the engine may have been swapped or atleast appart. So if anyone knows if its possible to ID a 3rz engine I'd appreciate the info, thanks.