Two Model Numbers Into One Item

I've been told something was impossible that I'm having a tough time accepting... I have a shirt that comes in green and black. Except for the color, they're the same shirt but they have different model numbers: 727980-010 and 727980-341. I've been told because of the different model numbers, they have to be different items. Is there something that would combine these into one item, have the user choose their color option and have the order reflect the correct model number?

Use the "Option" tab:

http://docs.opencart.com/catalog/product/option/

You'd think that would work but options do not affect the item's model number. I need the model number to change on the order based on the color choice... just as with every apparel SKU I have ever seen.