I think I am having to use the Data Validation tool for what I want to
do. The end result I want is this: I click on a drop down (lets say in
B3) and choose a dept such as "HR". Once I choose "HR" from the drop
down list, it will automatically pull the proper dept code (such as
10-53-24-1).

I was able to get this to work with multiple columns, where I would
choose "HR" from the list (in B3) and it's dept code would display in
B4. I want everything to display in B3.

From what I gather at this point, I would need two separate columns,
one for Depts and another for Dept Codes (I can create my drop down
from there with the Data Validation tool). I am having difficulty
accomplishing my goal.

I've tried using the REPLACE and SUBSTITUE functions, but I'm starting
to think that will not work.

Please help!

Try resisting the temptation of Cross-Posting over multiple NG's.

It means that your answer may be replicated and wastes people's time
when they could use that on other stuff.