The Stovebolt Site Forums The Parking Lot Big Bolts What is my engine?

I have a 1954 W6400 series. I assumed it had a 261 in it. I looked at the boss where the engine serial number is. Now I am confused. What is stamped on the boss is FI03IJ. What does that mean? I need a new starter bendix and just wanted to make sure I got the right one, before taking the starter out. The Starter ID is Delco Remy 107634 6H6.