How do you know whay year the motor is??

The 8th digit on your vin, if its a "1" then its an LB7 if its a 2 its a LLY as for the year of the motor I couldnt tell ya. My buddy has a LB7 and and as soon as you pop the hood you can tell the differance from his and mine (LLY) his has alot more blue hose couplings then mine which I have only 1 or 2. Also the LB7 doesnt have a calitic converter.

okay the the 8th number is a 2. Which year is it??And what is lly??

So you have an LLY according to your findings. May be an 04 aka, 04.5 or an 05. What is the build date on your motor? also, what is the vin number? You could have someone run a vin check to see what comes up for your truck.

okay the the 8th number is a 2. Which year is it??And what is lly??
An LLY. LLY is a rpo, regular production option, or some such nonesense. It is how the factory identifies what is going into the truck/car. It is a 4.5 if the truck is a 2004 model. The engines changed in late December from LB7 to LLY,
half way through the model year, hence the .5. If yours is a 2005 model, then you have a 05 LLY. There is really no difference.

Jim

LB7 has internal fuel injectors ,LLY has external fuel injectors and varible vein turbo.

Thanks guys, was just wondering what the diff. was from year to year. I bought my truck in July. I will have to run it through the vin. assist at work.