how do i know which crate i have?

[GMC Guy]

before i bought my truck the previous owner had installed a GM crate motor. now which one exactly is what i don't know....

it looked most like this one when i first got the truck, but i think there are a couple variations that look alike.
http://www.summitracing.com/parts/NA...7353/?rtype=10

then there's this one...
http://www.jegs.com/p/GM-Performance...52506/10002/-1

basically i would just like to know, how do i figure out which GM crate motor i'm working with?



the PO didn't buy the motor through summit or jegs, but i think through Groth Bros.