LS1Tech Resisdent Experts
The 5.3, infact, has the Dished pistons! The 4.8 has Flattop Pistons. The piston is clearly visible through the spark plug hole. This is a sure fire way to tell it's a 5.3. I almost couldn't believe my engine was assembled with head gaskets stamped 4.8, even though they are the same bore as the 5.3, and had Dished top pistons. So I flipped the motor on the stand and removed the oil pan, windage tray and oil pump pick up arm and low and belhold, there it was, the crank with the 12552216 casting number. It's a 3.622'' stroke crank. The 4.8 crank casting numbers are 12553482 '99-'00 with autos(and all trucks from '01 and up) and 12553312 in '99-'00 trucks with manuals, at 3.268'' stroke.
I hope this info is useful to someone. The 4.8 and the 5.3 usually run the same price at the salvage yards, so the extra stroke won't cost you a thing if you know what to look for!
The following are just two of the sites I found most informative:
http://www.enginebuildermag.com/Arti...all_Block.aspx
and
http://www.pera.org/articles/eb120317.htm
FYI: The 4.8 also has a longer Connecting Rod at 6.275''. All other LS motors use a 6.096'' Rod according to the mentioned sites.
Last edited by Cannonball1200; Dec 24, 2009 at 03:33 PM.


