I want to order headgaskets for my lq4 but im not sure what year it is its around 01 to 03. Will the mls and non mls gaskets interchange? Whats the difference between the two other than mls?

 

If the engine was originally equipped with Fiber type gaskets you need to inspect the heads gasket surface for a notch. This typically applies to LS1's and 4.8/5.3 engines. See attached picture.

You shouldn't have a problem either way unless you have the notch on the deck surface. If you have the notch, your only option is to run the fiber style gaskets. The MLS will not seal correctly.

As far as I know this only affects the 806 and 853 heads on the 5.7L LS1 and the 862 heads on the 4.8/5.3L

If your engine was originally equipped with Fiber type gaskets make sure all the deck surfaces are clean and free of pitting. If not, you may also have issues with the MLS gaskets sealing. The MLS Gaskets are a much better gaskets for long term use.

If you look down at the heads it's real easy to see if you have MLS gaskets already you will see a rivet holding the layers together.

 

Look at the vin number etched on the block, this will confirm the year.

 

I knew how to tell the difference between the two when looking at the gasket but the motor is still together and i wanted to order the gasket set ahead of time. Im not afraid of running the fiber gaskets thats all i ran on my old gen 1 motors.

 

The casting date is cast into the passenger side front of the the block deck but is not always legible and can be hard to read while assembled in the truck.

 

You should be able to see the edge of the gasket were the rivet is located in the right front of the block even with it in the vehicle.

 

^^ sweet i just couldnt remember if a fiber gasket could be used on a later model block. I thought i read somewhere that you couldnt.

 

It's not so much the block but the heads that will dictate it like I posted above.

FWIW the notch area can be welded up and milled flat so you can run MLS gaskets should any one run into that.

 

The vin# is etched into the deck surface on the driver side of block, look at the edge of the block directly behind the driver side cylinder head.

I ran a carfax report on what I thought was a worn out 200k mile 5.3 and it was actually a 2007 classic 5.3 with 11k miles.