i have a 2000 chevy with a 4.8 (according to the vin) but there is no real way for me to tell when i wife bought the truck the dealer said it had a 5.3 and i know they are the same block and to a certain year the same heads. but according to mortec.com i should have 862's but my heads are706's which were put on 01-04 5.3's. did chevy ever put 706 heads on a 4.8? if not i probably have a peiced together motor or it has been swapped. how can i tell the difference between a 5.3 and 4.8 on just a visual inspection? i am about to build the truck new motor trans and everything but if i have a 4.8 i want to get new crank and rods and pistons to go with 5.3 since bore and block are the same. or on another unrelated topic what is the difference between 4.8/5.3 and the 6.0 becuase if it isnt to much ill just swap the 6.0 into the truck and be done with it. any info is greatly apprciated. thanks jeremy

 

my 00' 5.3 had 862s, i bought a set of 706s off of idunno, both have 4.8 cast into the bottom of the intake runners, weird. i can't think of anyway to verify wether its 4.8/5.3 externally,

5.3/6.0 share the same crank but 6.0 has 4.00 bore, id buy a 6.0, do watever ya want to it and then sell the 4.8/5.3 to recoup some of the cost of the 6.0 .............. hope that helps

 

My 00 4.8 had 862's.

Definitely swap to the 6.0. There's no comparison with the 4.8 at all.

 

Take a spark plug out that's super easy to get to and gently take a screwdriver and feel the top of a piston. If the piston is flat from the edge and across the top it's a 4.8L. If you feel a slight dip or dish as youmove from the edge of the piston it's a 5.3L

 

thanks for all the info i think i am going to go with the 6.0 i can get one used with about 60000 on it for around 900 with all my discounts from work. next question is what cam? i want good low end since it is a truck and all the ls1 cams dont give enough *** on the bottom.

 

youll never look back after the 6.0 thats a wise decision on your part

 

I know it's a little late but I came across this looking for some other info and thought I would add to it

Mortec info Is not entirly correct.
I personal own a Silverado With a 5.3L that has 706 Heads on it from the factory. I beleve they were also avalible on 4.8L

The 862 heads are much more common.

I think it has to do with the casting process and what parts are avalible on the shelf at the time of the build. It may also have to do with what engine plant assembled the motor. Unfortunitally because of the casting process used for the 706 heads I don't see a casting date on them.

They use whats called SPM Semi Permanent Mold process. It produces a more acurate casting with minimal core shift. While the 862 heads use a more common Sand Cast Mold process making it easy to change the casting date.
The 862 DO have a date code cast into them

It said that the 706 heads can make an aditional 5 or more horespower over the 862 In bone stock form. Once ported though all that goes out the window.

Now with that out of the way the only way to tell for sure if its a 5.3 would be to attempt get a look at the piston through the spark plug hole. 5.3L have a slight dish while the 4.8L is a flat top...

hirdlej Explained another way to pyhisicaly check through the spark plug hole

Either way There is only Like 10 Hp differrence.

6.0L Would be a nice upgrade either way