Good evening gents
I've been lurking for awhile trying to versus myself on LS style engines.Here's my question i've got a couple of 03 trailblazer engines kicking around the shop,i wont to swap heads. I want to put on some heads from 2010 silverado 5.3L,which head bolts do I order the 2003 or the 2010 since there different. Thnaks for taking a look see and answering Luc

 

The head bolts are particular to the block. The pre-2003 have more than one length; the 2004 and later blocks are equal length.

 

Thanks, sorry to be a pain but y did GM do that ?

 

I don't know. My guess is that: (1) the change allowed GM to reduce the number fasteners it inventories at least prospectively; or (2) the change was needed due to some internal change in the block casting.