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Been there Done it
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Happened to be on wikipedia yesterday and read this interesting tidbit.
The Vortec 6000 LQ4 (VIN code "U") is a V-8 truck engine. Displacement is 5,967 cc (6.0 L; 364.1 cu in) from a bore and stroke of 101.6 mm × 92 mm (4.00 in × 3.62 in).
The 2005+ Generation IV 6000 is a V8 engine that displaces 5,972 cc (6.0 L; 364.4 cu in) from bore and stroke of 101.6 mm × 92 mm (4.000 in × 3.622 in).
Is the Gen IV really 5cc bigger or is it just a matter of the fact the info used to figure displacement was rounded down for the gen 3 and the .002 difference in stroke is not real.
Reason I ask is I have an 05 LQ4 that needs one connecting rod. It's a Gen IV with the floating piston pin. I have a new LQ9 rod for an 03 LQ9. The LQ9's used floating pins in all years, 02 up. My understanding was that the LQ9 simply had Gen IV rods in all of them whereas the LQ4 didn't change until 05.
If the difference is length is real then the LQ9 was technically a bigger engine than the LQ4 in 02-04. Albeit by only 5cc.
Probably worth .0003 HP
:unsure:
 

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03 GMC Sonoma SLS & 04 Chevrolet Blazer Ls
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They are all the same for the gen IV rods did a lot of research before I bought the gen IV rods for my gen 3 5.3L. it's the same part #12649190
for the 5.7L. 3.6L. 6.0L, 6.2L, 7.0L. 4.8L, 5.3L,
 

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Hardhead
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Rod length varies. Two thousandths is nothing, it could be covered by production tolerances alone. About the only way to get around it is to have the engine blue printed but you really pay for the priveledge.
 

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I rather have .002 positive then to the negative. It's funny how a 002 difference in deck height can make a minor difference in your compression ratio.
 
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