Here's my story. I ordered a new pinion seal from Moser, since mine had begun leaking. 4 days later, and it's the wrong one. I could tell because I was comparing it the one that came out of the car. Rather than wait another 4 days for the right part from Moser, I went over to Advance Auto, and a young girl was behind the counter. She looked about 12, but was probably a bit older.
I started in with "I need a new pinion seal for a 9" Ford, so let's start with a 70 Ford F-150...." She cuts me off, and says "Let me cross-reference the old one in your hand". She inspects it carefully, excuses herself, goes to the back of the store, and comes back up to the counter with a new seal. The right one too.
I was shocked.
jp