I am going to look at a motor and trans tomorrow, the guy says its a 5.3 but how can I tell that's what it is for sure. I just don't want to buy it and it turn out to be a 4.8. What are the noticeable differences?

Mike

 

Pull out spark plug and look for dished pistons with a flashlight/boroscope. dished=5.3 flat=4.8
Thats the only way I know of.

 

Double post.

 

what he said^^

 

That or pull the pan and look at the casting number, 12552216 is 5.3 casting.

 

yea at the right angle you can see down the spark plug hole and tell if its dished or not. might have to pull a few to find a piston close to the top.

 

The 6.0 I bought was cast into the block on the right side behind the alt. / ps bracket and on the right rear behind the flexplate. Its very easy to see if you remove one or the other.

 

Yah a 6.0, but a 4.8-5.3 have that on the block, not one or the other...

 

nothin but a peanut...

 

If The the engine and tranny is still in the truck it is coming out of then look at the 8th letter in the vin number,and the 10th digit will tell you the year model!!
V=4.8
T=5.3 (LM7)
Z=5.3 flexfuel
B=5.3 HO (high output)