Old Toyota Key Codes - what's the deal?

Ive got a 1993 Toyota Corolla sedan. My key was in bad shape, so I set out to find the key code and have a new key made. I did a little research and discovered that the code is supposed to be stamped on the passenger side door lock cylinder. I took off the door panel, got a bright light and a magnifying glass and, sure enough, I found three sets of four-digit numbers on the cylinder. Great! So I wrote them all down and took them to my local Toyota dealer. But the dealer just looked at it and said these can’t be the key codes. Why not, I asked. Because, I was told, key codes are supposed to be five digits (not four) and are a mix of numbers and letters (not exclusively numbers). The machine that cuts the keys cant accept any other kind of code. Not good. I went to a second Toyota dealer and got the same story.

The dealers tried looking up my key codes based on my VIN in their database but got bupkis.

Maybe Toyota changed their key code format sometime in the past? Or maybe there is another number on that cylinder that I didn’t see? (Though I made a pretty thorough examination with my magnifying glass I did not fully remove the cylinder from the door handle).

Anyone else run into this problem? Anyone know anything about the evolution of Toyota key codes? Any most important, does anyone know how I can find a key code for my car that can actually be turned into a key!?!?!

Thanks!

A cheaper alternative would be a lock-smith. Any good lock-smith will have access to that information and a lot cheaper.