how can i tell if my engine is orriginal?? and how do i know if it came out of a different car or truck?? i tried finding a number but the only ones i can find r on the intake manifold, and i cant see behind the heads

 

On V-8 mills look for a pad, front of block, underneath the right cyl head.


Bonus:

Auto Tranny code is located on the right rear oilpan rail and includes year, model, Julian build date with work shift ( 1st, 2nd, Day, Night shifts)

Don