So the block externally looks the same other than what's on the back of the motor...as in markings? The head castings seem like they are the only thing that someone would be able to tell the difference with...and even then...they would have to know their trash to know the difference between 317/243/706 casting numbers...
I think that the TBSS manifold on the 6.0 would make it even more legit looking because it looks like a truck manifold....I wonder if you could even screw that plastic vortec cover on top of it....I know my old SS had the same kinda plastic thing on the top of the motor with a wing nut but I never tried seeing if the truck cover was the same dimensions underneath....anyone know for sure?

 

Yep the 6.0 stamp would be on the back of the block and that would be the only way they would know, Besides head casting numbers, and like you said he would have to know his ****. And even then, The 08+ 5.3s came with 243 heads so for all he knows its a 5.3 from a newer truck..

 

Yeah and my truck is an 07 classic body style truck..so they made both body styles my year...I could pull it off if the dude asks and tell him that it's the stock motor and an "odd year" where it had all of the new **** in the older body style...LOL...I wonder if that would work...I bet it would work on a cop that doesn't look at motors all day every day....

 

Tell them its a lq9.If the smog tech pulls the head well...I guess its the chance you take.lol!

 

Man I'm glad we don't have to deal with that bs here.

I wouldn't think it would matter. Especially if you said it's a LQ9. The only way to tell the difference between a 4 and a 9 is to look at the pistons.

I would think dropping a LQ4 in, and using all the smog equipment from the 5.3 would work fine.

 

White1...I WISH that it was THAT easy...when you go in to have the motor "legally" checked out by the state to get your little sticker in the door....you have to bring the PAPERWORK from where that motor CAME from because they want to make sure that you bought it at a junk/salvage yard/private owner of a totaled vehicle....they make sure that the motor wasn't stolen, the year/make/model/ and ACTUAL VIN number of the vehicle that it came from....it's craaaaaazy when you try and do it legally...that's why I was looking at 07 LQ9's and sayin holly CRAP that's a TON of money for a motor, and started looking at LQ4'S...
The only thing that I haven't looked into is the legality of just buying an LQ9 short or long block from a junk yard with paperwork from a totaled truck....and then doing things THAT way because my accessories and everything will hook up and be enough...not sure about the alternator...but I have an 4:25:17 PM with power everything and a six disk...so it MIGHT have enough of an alternator to just use my 5.3 one.....what do you guys think about that short block idea?
An 06 LQ9 powered truck uses the same cats and smog equipment as the LM7 doesn't it?

 

OOPS...I mean does a 2007 LQ9 powered truck have the same smog equipment as the 07 LM7 trucks? I can't edit my previous post with my phone...my blackberry doesn't like the edit function...LOL

 

like i said before my truck passed with the 5.3 cats and all the AIR/egr stuff hooked up, use whats on your truck now, just change the motor out
the EGR/AIR was phased out on 02-03 models
unless a cop or smog tech really knew about GM LS motors then they might say something about head casting numbers, but its highly doubtful
a logo on the heads would stand out to some,but other than that youre safe

the 6.0 stamp in on the front and back of the block, how do you people not know that?

 

Wow, that is a lot of BS.

Wish you the best man. I think all the 1/2 ton trucks have the same emission equipment be it a 4.8/5.3 or 6.0 with the exception of the 1500HD which has dual exhaust all the way to the muffler. As far as everything else, it should all be the same. The only difference externally between the 4.8/5.3 and the 6.0 is the stamp on the block.
I know you want to do the swap the legal way, and I understand, but I would imagine that no smog tester, would search for the 6.0 stamp on the block unless he had reason to believe the engine had been swapped, also I wonder how many know every engine combination available for every year, make and model of every vehicle.
Then again, I could be very wrong, all we have in La is they pull a vacuum on your gas cap and thats your emission check, and they check the PCM for any codes. Its way harder to get away with illegal tint than any emission violation.

 

The ½ Ton trucks and SUV’s that were factory equipped with a 6.0L from 2001 thru the 2007 Classic’s had a different cross-over pipe than 4.8/5.3L engines. The 6.0L equipped models had dual individual pipes going all the way to the muffler. They also had a different heat shield on the passenger side of the transmission due to the proximity of the dual pipes running so close to the transmission. Having said that, the smaller engines hardware will bolt up just fine and no one would be the wiser.

For the most part, EGR was deleted from the engines after 2002. Engines from 2004 up were equipped with a returnless style fuel system. On a side note, all the ½ Tons that were equipped with a 6.0L were also equipped with ETC.

An LQ4 or LQ9 would be an acceptable replacement, as the LQ4 was used in the 2001 GMC C³, 2002 thru 2004 Sierra Denali, 2001 thru 2006 Yukon Denali, which were all ½ Tons. The LQ9 was used in the 2002 thru 2006 Cadillac Escalade, 2003 thru 2007 Classic Silverado SS, 2005 thru 2007 Classic Sierra Denali, 2004 & 2005 VHO, 2006 Vortec Max, which were also all ½ Tons.

As everyone has already said though, no one will know the difference from the outside if you don’t tell them. I was transplanting 502’s into dually’s out there for years and everyone just took them for good running 454’s. I do commend you for wanting to be legal, just don’t beat yourself up over it too much though.