Aluminum LS Block

[iamdub]

The L33 was marketed as an **, or Vortec High Output; something like that. The engine had a "bigger" camshaft which, coincidentally, is the same grind in our engines. That was the most powerful 5.3 Gen III engine. Not that the LM4 is no good, it's power rating is 5-10 hp less depending on the application.

Ah. So that's why it's "so coveted".

 

[okfoz]

I have a 2005 Rainier with the V8 Aluminum block as a parts truck, and a 2006 with the same Aluminum Block. One thing to consider when going to an iron block the front will sit lower because the weight of the cast iron is about twice that of Aluminum. If you are set on replacing with an Iron block, I would at least consider getting something other than the 5.3, get a bigger engine.

My wife drives that truck, and I really like driving it, the acceleration is great. Wife told me the other day she never want's anything but a V8, after she got in some traffic and had to get around someone.