Ls3
 

It may have an oil pan for a Camaro on it instead of a Corvette. Swap the oil pans.

2010 LS3 Camaro oil pan

https://cimg6.ibsrv.net/gimg/www.cor...0d4e174639.jpg

https://cimg7.ibsrv.net/gimg/www.cor...5007f97e16.jpg

That block casting number, 12621766, is an LS9.

An OE LS3 is an LS3 no what if it came in a Camaro or Corvette, ratings are mostly marketing with a very slight dose of intake and exhaust packaging. They are also a little under rated as they stand in crate motor form.

I wouldn't be shocked at all if late production LS3s used the LS9 blocks; why have two different blocks for the same displacement engine? There's nothing magical about the LS9 block, it's differences are all inside. GM did the same thing with late production LS1s a little after the LS6 came out.

ETA: I just looked up the part number from gmpartsdirect.com for an LS3 for Corvette and one for a manual Camaro; they are both 19256529.

Does this mean he can't use this engine on his bolt on stuff. Can the LS-9 even be run without the supercharger? Did someone select the wrong engine to ship to him or is everything okay?

On the side side of the block, opposite the GM embossed logo is "6.2L" on a '08 block, at the same location on a '10 Camaro, it's "LS3". I suspect the casting was changed to "LS3" so it wouldn't be confused with a "LS9".
The '08 block has PN 12584724. Some of the "windows" in the lower block are different between '08 and '09 to allow better airflow in the bottom end.

Since all LS9's had dry sump oiling, the crank nose is longer to allow and extra oil pump and the pan has oil line holes on the right side. Take a photo of the right rear and right side of the oil pan. The compression ratio is 9.1 to 1 vs the LS3 10.5 to 1. The boltons shouldn't be a problem, but you'll need to deal with the oiling. With the much lower CR you can run regular gas without pinging.:D

Ls3 or l99 I just wanna make sure the shop put the right motor in my 2009 Corvette