I have an '04 Silverado with the 5.3. The code on the glove box label say's LM7 which is a 5.3 gas with iron block and iron heads. My engine has iron block and aluminum heads which have a code of LMG. Should the code sticker not show the LMG code? Or are all 5.3 shown as LM7's??? It has the HD trailering pkg. and Z82 and 85 packages also. Thanks for your help.

 

im guessing you bought it used. so theres a chance that a previous owner put aluminum heads on the truck. do the heads look stock? It could be that it was a custom ordered truck and whoever was ordering it wanted aluminum heads to be put on it.

 

Yes, I bought it used. They do not look like after market heads. They do have a no. cast in and I'll check it tomorrow. I might go to the local Chevy garage and ask them. Thanks.