Hi All,
I just bought a salvage LM7 2004 Tahoe?
I confirmed its a 5.3 by checking the crank number 12552216
But I found it to have a 4.8 on the passenger side head gasket tab
also by feeling inside the spark plug hole the pistons appear to be flat top
I cannot confirm this yet as I haven't removed the heads.
The heads are 862s.
What have I got going on here?


TIA George

 

hmm

What's the vin #

 

Not sure of the vin
But got this off the block
Near trans left side rear flange 4J304114
and on a small flat area near other number is this 28012700 : 17

 

If the crank says it's a 5.3 crank then that's what it is

http://www.lt1swap.com/identify_vortec_engine.htm

 

Thanks Burken01 clipped form LT1swap.com


ENGINE SIZE SPECIFIC INFO
Vortec 4.8 / 5.3 differences: GM used a shorter stroke crankshaft in the 4.8L and a longer connecting rod. 99 to 03 or so, the 4.8L's all had completely flat top pistons. 5.3L's had a slight dish. However, after about 2004 sometime, the 5.3L's could have true flattop's. So really the BEST way to tell is measure stroke, or casting number on crankshaft. Of course if you are standing in-front of a vehicle, you can look at the VIN#. 8th digit is the Engine, 10th digit is the year. T = 5.3L LM7, V= 4.8L LR4, Z = 5.3L L59 Flex Fuel (1999 to 2007) Typically 1999 to 2002 were cable driven throttle bodies, however, some did get drive by wire as early as 2000 I have seen.


So only question left unanswered is the 4.8 head gasket the same as 5.3

 

Same Bore Size. So to answer your question, Yes the 4.8 and 5.3 share a common head gasket.