Replace data in one column automatically based on another column

I have a column with 3 letter codes representing different manufacturers. On another sheet I have a column with the same 3 letter codes in one column next to the products they make. I added a number next to the 3 letter code on the manufacturer's sheet and will later removed the 3 letter codes to have just a number representing the manufacturer so I can import into Access. (I prefer using an auto number for my unique ID). Is there a way to automatically replace all the 3 letter codes on the products page with the 'number, 3 letter code' I created?
Example:

Manufacturers Sheet:
1,ACO
2,ACP
3,ACS
4,ADV
5,AEI
6,AER

Products Sheet:
ACO
ACP
ACS
ADV
AEI
AER

Problem solved... I didn't understand VLookUp at first.