1bdbrd

iTrader: (12)

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.

viewsonic

Gen.III, "LS1", aluminum 5.7L 350ci

1bdbrd

iTrader: (12)

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.

1bdbrd

iTrader: (12)

anyone?

70 LS1

iTrader: (1)

It is indeed an LS1 5.7L block. Google is your friend. Why do you care what year the block is?

12562174...350...98-up...crossbolted block, Gen.III, "LS1", aluminum

1bdbrd

iTrader: (12)

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.

erikerikerik

also has to do with oiling, nothing wrong with the 98. however the 00' was the next revsion.

Stu Cool

iTrader: (13)

There should be a laser etched number on the driver side of the block just behind the where the oil filter mounts to the pan. With that number you can determine the year and possibly convert it to the VIN of the original car.

Pat