How to know the difference between the vortec 5.3 and 6.0 and 6.2?

The Chev 5.3 and 6.0 (also the 4.8) look the same on the outside. The 4.8 and 5.3 used a 96mm bore. The 4.8 83mm stroke, 5.3 92mm stroke. The 6.0 had a 101mm bore with the 92mm stroke. Even if there were slight differences the guy may have gone out of his way to hide em. The 6.2 from the factory did not look much like the older ones and had lots of high tech internals but the basic external bits were pretty similar to the earlier ones so you may be able to so some swapping. Back in the old days when many races were limited to 350 motors people would take the 400 blocks that looked like 350's then internally balance them so they looked just like a 350 on the outside but had the extra 50 cubes on the inside. Once you start modding things anything is possible.