it's not as big of a difference IMO as the modular fords...the 4.8's really only lag behind off the line, once they're moving they'll stay pretty close to a stock 5.3.

 

Not sure who told you that, but that never happened.

As for a 4.8 making it in place of a 5.3, from the factory. I suppose it 'could' happen, but is so unlikely that I'd have to personally witness it to believe it. You sure its a 4.8L? You measure the bore/stroke? Any of the bolts in the engine compartment look like they've been removed, as if the engine were replaced?

 

I tuned an LS2 GTO with a tune that read 5.7L. No explanation as to why...**** just happens I guess. I'm sure his tune says 5.3L lol.

 

Now that did exist on some of the tunes. The TBSS LS2 tune was the same way. That really doesn't do anything to the tune though, and was probably just skipped over when the final tune was approved.

 

Original owner has all the dealer service records from new all the way up to a month or so ago. He had all service and maint. done at the same dealer from new. All the dealer records show 5.3l along with the original window sticker and the vin all say 5.3l.

The drive train was 100% stock I am 99.9% sure on that. If they did swap the motor they were pretty good, i didn't see any marks on any bolts ect...that you would normally see. All the wiring ect. was untouched everything was in its place even had all the factory labels on everything. The tune was for a 5.3 on the stock ecm. The motor has flat top pistons and had a stock factory 99 cam, unless they accidentally put flat tops in a 5.3l in 99 it has to be a 4.8l.

 

Not really, I drove a bunch of them before I bought my truck and the difference is very minor. Now with same mods, a similar 5.3 truck you can really feel the extra tq. Sub'd for outcome. Of course when your talking about the 99 models, the 4.8s were way down on power compared to the 5.3s.

 

If that was the case... Id have a lawyer and a new denali sierra in my driveway.... If a lady can sue for burning her lap with coffee...

 

Seriously?The only thing a 5.4 does better is drink gas.I currently have 3 modular fords and wont ever have another 5.4,especially a POS 3 valve headed one...I run my 4.6 supercrew against a friends 5.4 supercrew and he took me by maybe a truck length and that was with a fiberglass toneau cover and heavy *** lightning wheels on my truck and his sitting on stock 16's.I'm a Ford guy but a 5.4 really is a damn joke for it's size compared to a 4.6.SORRY for the thread jack guy's... A 5.4,