I was wondering if this was a drop in swap. I know the 03+ 5.3 are drop in but would the wireharness and pcm and t56 transmission work with this? Can I literally drop the motor.in.and go?

 

I'd advise that you use the search button at the top of the page, I'm sure there are plenty of threads discussing this topic already.

Yes, the 5.3 will fit. Yes, you can mate it to a T56.

You will obviously have to make some changes as far as the wiring and PCM go, I don't know specifics on this though.

Do some searching and you should find what you are looking for.

 

There are minor differences. But if you plan to swap over the oil pan, FEAD, intake, etc. and as long as the 5.3 is still 24x, all it will need is a tune.
The biggest difference should be the location of Knock sensors.

 

Any 5.3 will work as long as it is 06 back. You do not have to move the knock sensors there are no wiring changes to be done as it's the same as your 5.7.

You need to use all of the fbody front accessories, fbody oil pan, exhaust manifolds or headers if your car has them, coil packs and bracket, and your upper intake and fuel rails and the LS1 clutch and flywheel will work on the 5.3 you just to put a pilot bearing in the back of the crank no biggie.

Then of course have someone do a tune on it so it will run correctly. It will start and run on the 5.7 tune but will require a retune to optimize everything.