WranglerGM

How can I tell the difference between a 4.8 and a 5.3 Vortec? These are all the numbers I found on the engine, and still I can not see the light:
left side, back on the side of the head
0335503666738925
oil pan:
12577396
F 9
GMPT
right side back on the side of the head:
3355C7453924
Corner of the heads on the top:
862
Back passenger side ledge of the block:
2567393
This last number is really strange since it has only 7 digits versus all the number I've seen that have 8 tigits tipically. I hope I have a 5.3, because this is what I was told when I got it. Can yo please help me?
Thank you
Paul

NOSjohn

iTrader: (9)

12561358...325...99-up...Gen.III, used with 5.3L motors

^^ That is one block number. I may be wrong, but I think that's the only production number.

WranglerGM

So, could I say that the engine I have is indeed a 5.3? sorry if I insist but I am really at the first stage of this....
Thank you
Paul

Gloveperson

iTrader: (9)

I am pretty sure you have a 5.3

You could always do it the hard way of actually measuring and all.

-Todd

WranglerGM

Come on guys! Anybody with a clue about this subject? I'd like to hear some more ideas! I called Advance Adapters and a nice guy told me to email him the numbers which he will forward to someone that will look up and see if he can trace the engine.
Paul

B3Enterprise

here is the link for you:
http://www.pera.org/CoreTalk/eb120317.htm

WranglerGM

Finally: thank you very much: tomorrow I will perform the test; I am scared because I have already the engine installed, but I have to find out! Thank you and have a nice week end.
Paul

TD's z

the number 862 on the top corner of your heads is a casting number the heads are 5.3 heads...if it was a 4.8 it would say 706 in that place

strokedls1

iTrader: (1)

I have seen both head casting numbers on 5.3L engines. We have broken down four blocks a while back with both casting numbers.

WranglerGM

HOw is it possible that GM makes two different engines and it is impossible to determine the displacement just by looking at some numbers? So I would say even when you buy a new Yukon yuo could get a 4,8 thinking of buying a 5.3 and never be able to know it just by looking at the engine! It sounds stange to me. I will have to take off a spark plug, and let me tell you, the position in which they are located doesn't allow to have a straigh sight through the hole. Expecially when the engine is already in the vehicle, that is my case.
Paul

NOSjohn

iTrader: (9)

I would think you would be able to put your pinky finger down the spark plug hole, when the piston is TDC, and feel the "ridge" in the 5.3L piston dish. If your finger is too big, get your little brother, sister or girlfriend and try to see if they can feel it. I've done this before on some 1st gen. small and big block motors.