i wanna know if i can switch them out and have nobody notice the change.

 

there is a marking on the block on the front and dont remember if it is on the back. it is cast in the block and says 4.8 over 5.3. all they do is put a yellow stripe over the number acording to which motor it is. So you could paint it black and no one would know. but to answer your question you would not be able to tell. It is on the driver side under all the accesories so you could put what ever in it like a 6.0

 

I believe the 4.8, 5.3, and 6.0L all look the same on the exterior.

 

Here is a pic of what Sleepersilverado is talking about, except mine did not have the yellow stripe.



This area is normally covered by the power steering pump. The two holes above the number go to the water pump. The 6.0L is similar except it says "6.0L". I can get a pic of it for you if you would like. Since 4.8's and 5.3's share the same block, there are no marks to tell between them.

EDIT: Sorry, pic should be there now. PT.NET is acting weird today. BTW I checked my LQ4 and the block is marked on the back, but on the passenger side. This might be visible with a mirror without any disassembly. Will check on my truck later.

 

with the exception of the casting numbers being different on 6.0L heads and the stampings in the block mentioned elsewhere in the thread you are absolutely correct

 

Remind me never to buy anything from you.

 

:crackup: HAHAHAHA

But seriously you could be a real bastard and bore it out to a 5.7L and put a set of really worked 5.3L heads to have a high compression iron block LS1

or you could do that and drop a 4" crank to get a 383

 

that's awesome..

we actually did this on 1BadC10's Yukon, he threw a rod in the 5.3, stuck a 4.8 in it and he sold it two or three days later. Honestly I didn't know he was gonna sell it that fast, but he wanted nothing to do with that truck after that.

 

also on the airbox it says the size of the engine...just thought id throw that out there

 

thanks for the info.