I have a friend with a 2000 F350 4x4 4door longbed 7.3 auto. He bought it used with about 100k.

It runs good and strong. Blows some good black smoke on acceleration.
Many think it already came with a program installed. Is there any way to tell what's in there?

pull the ecm out, it is beside the parl brake. See if there are any modules or boards plugged into tht back. This is the most common way to install a chip on a 7.3

Larry had the truck at a performance shop and the vendor looked down below the dash and also under the hood. He said that he could not find anything but he felt the truck ran better than stock.

One other thing we noticed was that with 255/85/16 tires the speedometer was dead on. Those tires are about 1/4 inch taller than a 285. So basically 33" tires. That is why I figured it had to have downloader rather than a chip/module.

He said the Ford dealer would reflash his rig for 43.00 dollars. I asked him if he was prepared to spend 400 + for replacment power. Larry said he would not care if he lost 50HP. He said he never uses it. I lauged. I told him he would be sorry.