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dwcsr · 06-23-2012, 12:17 PM

The 4.8/5.3 use the same block with the 4.8/5.3 designation cast into it.
The older 4.8 had dished pistons and the 5.3 flat tops prior to 2004 after 2004 they both had flat tops. The crank casting number is the only way to tell for sure or if you have the PCM get the vin and it will also tell you.

I was told that on the casting 4.8/5.3 on the front there should be a paint mark that covers either 4.8 or 5.3 and that is the way the factory new which was which on the line. It did on mine but it may not actually be correct, I only had one motor to check it on.

06-23-2012, 12:17 PM	#6
dwcsr Hollister Road Co. Join Date: Apr 2005 Location: Houston Posts: 6,131	Re: How can I tell the differense between 5.3 and a 4.8 liter LS motors The 4.8/5.3 use the same block with the 4.8/5.3 designation cast into it. The older 4.8 had dished pistons and the 5.3 flat tops prior to 2004 after 2004 they both had flat tops. The crank casting number is the only way to tell for sure or if you have the PCM get the vin and it will also tell you. I was told that on the casting 4.8/5.3 on the front there should be a paint mark that covers either 4.8 or 5.3 and that is the way the factory new which was which on the line. It did on mine but it may not actually be correct, I only had one motor to check it on.