That number is ***** a serial number.
6NC00001-UP; 08Z0001-UP are in older series D7R machines and are 3306 engines.
7ZR00001-UP are in newer Series II D7R machines and are 3176 engines.
The valve cover should have a decal with the serial number. It should also be stamped in the block on the side near the cylinder head, usually near a corner.
If you have the decal, please include the arrangement number, that details the engine build and can verify the serial number is *****
If the engine was rebuilt by a NON-CAT dealer, all the numbers could be missing and it may not even be a true CAT engine. The 3306 is getting some import replacements showing up in the US. I have seen one but, it was ordered for a D6D and looked like a good match. We will see how long it will last, it is only a month old currently.
If you need details on the tractor, please post the machine serial number and I will get the original engine details for you.