I just picked up a 6.0L core of unknowen year the last 3 of the block casting number are 184 vs 364 like the other 04 and older blocks I have here. Is this the number for a 2005 up block?

Thank's J

 

No.... I need the number off the pass side of the block on the deck surface right on the pad in front of the cylinder head. It'll start with a letter then 2 or 3 numbers after it

 

Just as Joe said, to truly identify what year block you have, you will have to read the date code and not try to just rely on the casting number. Below are just some examples of casting numbers GM used for iron 6.0L’s.

12551364...364...99-06...crossbolted cast iron, Gen. III, 6.0L, truck
12573581...364...99-06...crossbolted cast iron, Gen. III, 6.0L, truck
12577184...364...99-06...crossbolted cast iron, Gen. III, 6.0L, truck

 

The numbers are hard to read but looks like J025 or maybe J625.

 

I am pretty sure the year is stamped on the side of block, Ive seen it on a few blocks.

 

No year on side of block but the date codes must be like the early GM blocks.25 must mean 2005 because it has the ls2 style rods. I thought It was going to be an o5 but the tech I bought it from said it was a 2003.....

 

J is the 10th letter of the alphabet so your block was made in OCTOBER. The next two numbers means 02(the 2nd day) and 5 means 2005. It's an 05 motor unless someone has replaced parts in it. The block is an 05 anyways for sho!

 

on the passenger side of my block (bottom, next to oil pan across from where the oil filter is on the other side of the motor) it is stamped 12573704

I have googled the hell out of this serial number/casting number and cant figure out what type of block it is.

I have 241 heads, aluminum V8 block and truck intake

It is literally driving me crazy that I cant figure out what type of car/truck this motor came out of.

Please help!

 

Could you be looking at a number stamped on the oil pan? Look at the end of this article.

Gen III GM Small Block: Engine Builder

 

you must be right about the oil pan because the numbers match.

I wish someone had a picture of where the serial number is on the block (i am told near the oil filter) so I can easily find it.