Are they the same motor? I thought the 5.3 was not a LS motor. In the Trailblazers, Envoys, and Rainiers they call it a Vortech 5.3 but in the Monte Carlo SS and Grandprix GXP the guys over at LS1tech.com are calling it a LS4.
So which is it or are they 2 different engines?

The 5.3 in the truck isn't the same as the 5.3 the impala. The impala uses D.O.D= displacement on demand where the trucks run on all 8 all the time the D.O.D engine looks to be nightmare from hell if it ever has a problem from a GM techs point of veiw

I see, it just seems a little strange to me that they would make 2 versions of the aluminum block 5.3

For 06 GM has 4 5.3 in there truck lineup if your planing a swap I personally would use a "Z" vin 5.3 this engine is designed to burn E85 thats if you can find E85 in your area I'm thinking that it's an all aluminum engine but I might be wrong on that If you have any other questions just ask

It would be nice to get the one that can run on E85, but if the recyclyer wants a lot more for it because of that then I will stick with the regular aluminum block 5.3. I wont be buying until late september so I have some time for people to smash those new ones up :grinpimp:

I purchased an '06 5.3 2 months ago it is cast iron block and aluminum heads I got lucky and found one with 5k mi everything to make it run for $1600 I would think about finding an '05 cause the new ones are fly by wire I am kinda worried about that gas pedal sensor getting dirty and stranding me in the trails. I also heard that they stopped using the alum block in the trucks for '06

Just for info all (DOD) engines are aluminum, most of the 07 Yukon's and Tahoe's will have these engines. These engines will be 5.3 and 6.0 liters. All (DOD) engines have 2 cylinders on each side that have a double lifter set up in each lifter bore. The (DOD) is controlled the actuators and oil passages in the valley cover. You can use a valley cover from a 06 GTO 6.0 to eliminate the (DOD) also i believe regular lifters will work in-place of the double lifter set up. As for fly by wire you can swap on a older manual t/b you just need to have rework the program in the Pcm. Note all of the aluminum V8 except the 7.0 ZO6 motor will be cast for (DOD) so you may be able to get a deal on one of these engines at a wrecking yard. I will check to verify the lifters can be swapped tomorrow. My .02:grinpimp:

Are they the same motor? I thought the 5.3 was not a LS motor. In the Trailblazers, Envoys, and Rainiers they call it a Vortech 5.3 but in the Monte Carlo SS and Grandprix GXP the guys over at LS1tech.com are calling it a LS4.
So which is it or are they 2 different engines?

THe LS4 is a all aluminum 5.3 but is it's own block (the bolt pattren to the trans is differant for the front will drive application and will not work with the standard rear drive transmissions). All the Gen III engines will basically interchange part wise. The LS2 LS4 are Gen IV engines same basic engine as the Gen III's they just moved some sensors around to make room for the Active fuel management system (DOD). And switch to a different crank pick-up ring as well.

The made aluminm block 5.3 in the SSR and some trucks. But I am not sure I what the differance in the E85 engines and regular fuels are. I know the tunning on he computer is different. I would just buy a iron 5.3 they only weigh 70 pounds more than the aluminum blocks and they would be far cheaper!

Well that makes sense that they would keep the alum block it was just gossip then. Anyway I am looking for a good company to do the wiring and flashing anyone have an idea of someone that is not too busy. I called waitformeperf. and he is months behind I think it has something to with price $300 for the strip down and flashing. Is there anyone else that is near that price, Quality is important my ride is looking pretty good so far dont want to ruin it now.

Speartech will make a harness or mod a stock harness. Check LS1 tech for tuners.

Or find some one locally to tune it with HP tuners.

As for the drive buy wire it's on the 2003 and up motors BTW! unless you going under water it should work fine. And I believe the new trucks don't have the contolr box for the drive-by-wire petal. It's just plug and play. The 2005 up trucks came with E-fans so the tuning and computer is already to run them.