Is it an LS1 or LS2?

[BrandonWood]

Can you look at an LS1 and/or LS2 and tell the difference based upon a visual inspection? The motor in question is not in a vehicle & does not have the PCM... At the time of purchase I was told it was an LS2, now another guy who works in that shop said it is an LS1 - now what??? Help!
The Heads are 241 heads, but this is an aftermarket motor - heads are CNC ported, etc...

[ss.slp.ls1]

Look up the casting numbers.

[BrandonWood]

Any idea how to look up the casting #s and where they are located on the motor / block?

[ss.slp.ls1]

If there's no tranny/bellhousing attached, look at the back of the block, behind the flexplate. There should be a casting number on the passenger side, write down and post all that you see.