4.8/5.3 junkyard motot identification

[tenerec]

I've located 4 ls motors in a local junkyard and I want to see what they are before buying, but I can't seem to find a way to decode the dot matrix serial numbers. Is there any way to decode these without buying an alldata subscription?

[txarkitekt]

The 4.8L block carries a 12551358 casting number. This block was used from '99-'04 for all the 4.8L motors. The 5.3L engines had a longer stroke than the 4.8L, but they had the same bore so they shared a common block. All of the '99-'03 engines and most of the '04s came with the 12551358 cast iron block, but there were a few that had an aluminum block... Both of these engines share a common aluminum head with 71cc chambers... The 12559862 casting was used from '99-'04, but the 12561706 showed up on some engines in '04, too. The 862 casting came with and without the recess on the edge of the deck surface... It also depends on what year motor you are looking at--all of the 5.3L engines got the LS1-style heads with the "Dee"-shaped exhaust ports in 2004. The dished pistons were replaced by flat-tops too. The 4.8L piston is a flat top, but the 5.3L is dished because they both use the same head, so the 5.3L with the longer stroke would have had too much compression with a flat top piston.

[tenerec]

So, there's no way to tell whether it's a 5.3 rather than a 4.8 other than pulling the pan or heads? I thought that there was some way to tell by the numbers stamped in the back of the block.