It looks like you're already done from here! Both part numbers are the same!
Without knowing everything about your schema, triggers, etc. it is really hard to guess what might be required. Specifically, does the database include DRI and/or triggers that implement the UPDATE CASCADE functionality. This problem is equivalent to "I need to replace all of the 3 mm bolts in my car" because without knowing more about your car there is no way for us to guess how many bolts there might be, where you need to look, or what problems you might encounter.
Finding all of the instances of a string is easier, especially if you can use Full-Text Search functionality. Even once you've found all of the occurrences, replacing them with something different is a much larger problem.
In theory, theory and practice are identical. In practice, theory and practice are unrelated.