Just bought a LS6 short block and am having trouble making a definitive identification of the year. This is important due to the cam difference in the 01 and 02 LS6. The seller mentioned he bought it from someone that had some type of affiliation with GM and said something about a GM tech facility. The block casting (12559378) is the same for both years but the laser etched code on the driver side flange (opposite side that the starter mounts to) isn't there...which would have told me what I need. Instead of the laser code there's a stamped number with several digits in the middle scraped over. What I can read: 115xxx66 or 115xxxx66 (8 or 9 digits).
Below that are some stamped letters/numbers: K034 and under that 877. Another unusual mark is a row of 3 dots stamped vertically between these 2 number sets. Here are some pics. If this looks familiar to anyone or if you need more/better pics or information, let me know. Thanks

 

well if you have just the short block pull the rear cover and look at the cam PN
01' 385hp cam- 12560950
02'- 405hp cam- 12565308

hope this helps

 

I knew the cam would solve it but I thought I'd have to pull it. I didn't know you could see the numbers like that. Are you sure? Thanks

 

There should be a born date on the rear cover of the engine. If its the original cover that came with the block. Its etched in.

 

There is...1711401. How do I decipher it?

 

Can anyone help me identify this from the code? Just need to know if it's a 2001 or 2002...big difference between those. OR...tell me who can? Thanks

 

if you have a dimple on the front top of the engine right before the intake manifold right under coolent crossover lines then its a LS if you dont have a dimple then its an LS6 block

 

its a 01 and up... so ls6 or not its still a good block...

 

Im gonna bump this back up for anyone who knows how to decipher the date code on the rear cover.

 

Anyone ever figure this out? My car had the motor replaced in it before I bought it and I need to know what year it is too so I can order the right parts. Had the same casting numbers (12561168).

 

all i know is that your car now has an LS6 block.. and parts should be interchangable wheather its an LS1 block or LS6...

 

With an LS6 block, how do you tell which head bolts to order? The ones with the 2x medium length bolts or the set with all long bolts?