I am doing some engine work on my '01 5.3L, and placed a large order with GM last night. I found all of the parts with the part numbers, which are claimed to fit all Gen III LS motors from what I could tell. However, the site that I ordered them from says the parts fit various years from 1999 to 2010. I submitted my VIN to them also and they emailed me back pretty much wondering what the hell I was doing with all of these different parts.

Here are the part numbers I ordered, in the same order as the screen shot (the screen shot doesn't have the part numbers on it):

12557840 Balancer bolt
12585673 Front crank seal
12574294 Timing cover gasket
12533586 Intake valve stem seals
12457652 Exhaust valve stem seals
12575329 Head gasket, MLS
12630223 Water pump gasket
12617944 Exhaust manifold gasket
12551933 Coolant crossover tube seals
12498545 Head bolts
12584922 Oil pickup tube o-ring, red

Here is a screen shot of the order. Thanks!

 

manifold gasket# looks right with what i have written down, sorry only thing out of those i have..

 

gmpartshouse?

 

Not quite, but it was one of those generic online GM parts place. I hope their service is decent... At least they emailed me about the potential problem

 

Curious as to what the potential problem was?
#12584922 red o-ring is the only thing that might be an issue. Could be #12557752 green o-ring.

https://www.performancetrucks.net/fo...d.php?t=428941

Head gaskets is a toss up deppending on when it was made. Originally that year might possibly of had fiber type head gaskets instead of MLS but MLS should work unless you have real early 862 heads. Picture attached will show the issue with the early heads wich require a fiber type head gasket.#12457116 -4.8L/5.3L GM Graphite Head Gasket