How can you tell the difference in the two since they both use thr same block?

 

Are u talking about the heads? As far as I know there is no difference. Someone correct me If I'm wrong.

 

I need to know how tell the diff between the 4.8 and 5.3 motor they both have the same casting number.

 

No, I talking about the block I think all's the same except thr stroke. There should be a way to tell the diff on thr bloke somewhere

 

Man I have to change this keyboard!

 

The blocks are identical. They are even stamped 4.8/5.3 from the factory. The only major difference in the engines is the stroke/crank and rods. The crank and rods from the 5.7 LS1 motors are the same as the 5.3 motor. The 5.3 differs from the 5.7 by bore only ( also iron vs aluminum ). Here are the numbers:
Engine Bore Stroke
4.8 3.78"/96mm 3.48"
5.3 3.78/96mm 3.62"
5.7 3.90"/99mm 3.62"
6.0 4.00"/101mm 3.62"
I'm pretty sure of the numbers but the GM website has them all. FYI, I am having a 5.3 block bored out to 3.898 and using stock LS1 heads and pistons. I have a post in the Internal section and it leads to other threads on the same vein. Hope it helps.

 

Great info Thanks!!!

 

The 4.8 and 5.3 have the same heads.