What block do i have?
#1
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
ok i was told this block is from a 99 trans am. it is indeed an LS1 block as it says 5.7 on it on the back i think. casting number from below the head is 12562174. the "How to Build High-Performance Chevy LS1/LS6 V8's" book i have doesnt have that casting number for ANY Gen III block. But a few pages later (page 43 if you have the book) it lists that casting number as a 6.0L iron block. so what do i really have? its an aluminum block for sure but i want to make sure its a 99.
#3
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
i figured it was an ls1 but i really am looking for what year it is. i did a search on here for that casting number and everything i found (except for one) said that its a 98+ block. one guy said he has that casting number in his 99 z28 so that reaffirmed me, i just wanted to make sure.
#6
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
i pulled up that same info but i didnt know if i could find year specific. i thought i had read someplace that the 98 block wasnt as good as the 99+ blocks. something about you cant hone it or something like that? i was just wanting to make sure as im gonna be rebuilding this one and ill need to hone it for the new pistons and rings.