the numbers on my block are 12577184. can someone tell me the year I need to know for headbolts and main studs thanks!

 

Used in 2003 & 2004. LQ4/LQ9 6.0L (377 cid). Iron block with 4.000" bore.

 

so pre 2004 head bolts?

 

Not to hijack but is there a way to tell which block is original to a certain car like with the "Numbers matching" 60's muscle cars? Did they stamp the blocks with the vin # like in the old days? I highly doubt it but thought I'd ask.

 

OP, you just need to see where the middle set of head bolt threads start. If they're just inside the holes, it's the later model block. If they're down in a few inches, it's the early model. I keep a few of the long bolts handy to check with. I have 2 LQ4 blocks, one early, one late and drop a bolt in to see which one I'm messing with.

 

the one that go directly through the center of the head?