ErikSOCAL

iTrader: (1)

Going to look at a 5.3 pullout from an '07 Tahoe tomorrow. Its complete with the transmission and all accessories except for the ecu.

I've looked through here and about the only thing I can figure out on how to tell the difference between a 4.8 and 5.3 is by looking at the crank casting number and if the vin is present, the 8th digit.

only problem is, I don't think I'll be able to get to look at the crank that easily and don't think the vin is present anywhere on the pullout?

How about determining year? I found one link that stated the front passenger side deck pad. Don't think its visible with the heads on though, is this true?

I doubt the guy is going to let me tear his engine all apart are there other ways?

thanks

GMCtrk

iTrader: (27)

I don't know if it's still true, but I believe the 4.8 has flat top pistons and the 5.3 has dished pistons. So you should be able to run a screwdriver into a spark plug hole and drag it lightly across the piston. If it's flat, you got a 4.8

ap2002

iTrader: (8)

the heads on the new 5.3's have 799/243 castings i believe...

nighthawk08

so do the gen IV 4.8's though.

nighthawk08

I dont think this is valid for the Gen IV V8's

philntx

iTrader: (8)

Look at the RPO codes in the glove box. If you see LY2, it's a 4.8

ErikSOCAL

iTrader: (1)

the glove box or entire vehicle isn't around!!!

philntx

iTrader: (8)

Ah, you didn't mention that in your original note. Does the seller have a copy of the title from the original car?

rgvsierra

iTrader: (7)

i think you can determine what year that motor was from by pulling the valve covers and seeing some numbers and letters engraved in the cylinder head.

ErikSOCAL

iTrader: (1)

I am hoping for some sort of papers but not holding my breath..

I believe the numbers are under the head on the deck pad passenger side. If anyone knows for sure, please correct me.

Man, I didn't realize how hard this could be. I guess back in the day people with 327's and 350's probably had the same problem.