Now I hope this doen't come off as a stupid question, but when I'm reading replies from other members I notice that some put thier vin code for an option on thier truck. What is this identifying on the truck for others to know. I have broken down my vin before on my trucks so am curious to know what I should be looking for.

It is the 8th character in your vin #. An "s" is the L56 motor with an EGR and choked up intake. "F" is the L65 H.O. version with no EGR and about 10 more HP. Leo

The eighth position in, on the vin, is the letter designating whether the engine has the full meal deal of vacuum operated goodies, like a EGR valve (S engine code) or it only operates the wastegate (F engine code).

IIRC the S engine is mostly on the lighter trucks, and the F is on the heavier duty models.

The EGR recycles dirty exhaust back into the engine, and is often blocked off or removed completely, but if not done correctly can throw codes. The F engine intake is a little better breathing as a reult of not having the EGR in place.

There are other differences, but those are what I have picked up here.

Cheers
Trev

Can't forget about the Vin "P" which is a naturally aspirated engine (non-turbo).

I've been curious which engine I had. An F, thanks.

ok...thanks...i have the "S" code then for my blazer. guess this means theres an improvement i can do to make a bit more power.

9294chevy you can get a 45mm freeze plug to block off the egr opening in the lower intake and then go to the link below for how to gut the intake. and it also talk about the little metal gasket do not lose this as it will help seal the plug in place.

http://www.kennedydiesel.com/
Go to 6.5 parts and then look for tech tips.

Ryan