ECM question

Hello everyone.
I am new to the site and I had a question about my ecm. I got an ecm and harness from a guy that had given up on a project, it is from a "04 half ton" in his words. I worked in a GM dealer for about 15 years so I knew he had no clue about it. As I was modifying the harness for my project I learned that it is a 04 6.0l with a 4L80e. I have already done all the harness modifications so it will run my 5.3 4L60e combination.

My question is: Can I download a stock 04 file from the repository or do I need to go to the dealer and have them program a VIN for an 04 5.3l with 4l60e?

Thanks in advance.

If you haven't linked the vin in hptuners I'd take the ecm to the dealership and see if one of your buds would flash it real quick for you. Only downside is you're going to have to come up with a VIN with the parameters you want. It can get tricky especially if you want to set up a certain type of AC system.