Car Stereo Locked - '98 Chevy Malibu

Guys, we really need your help with this one without spending the $40 or so asked by the dealership...

Recently, the car's battery had been replaced.  As a result, the car stereo's anti-theft feature locked us out.  The problem is that we do not have the security code (three-digit code) to unlock it.  After 8 failed attempts, "InOp" appears on the display and we must wait one hour with the engine on before continuing.  There was a number written on the car manual, but it turned out not to be the code at all.  We have gone through the proper steps* of entering the code, along with 8 failed attempts. 

Now, it was also suggested that the code is also located on the back of the stereo itself.  We may attempt to disconnect the radio as a last resort to view the backside.  We also do not have access to a decoder (without paying for one).  Alas, it seems that taking it out of the dashboard is the best thing to do.  The password is any number between 001 and 999.

Do you have any suggestions?  Please post them here or e-mail me directly. 

Thanks!

JoeE

* Here is the procedure:

1.  Put ignition in the ON position

2.  LOC will appear on the display.  Press Mn until the last two digits of the passcode appear as the last two digits on the display.

3.  Press Hr until the first digit of the passcode matches the first digit on the display.

4.  Press AM/FM.  SEC will appear on the display if the correct passcode is entered.  Otherwise LOC will reappear.

5.  After the 8th failed attempt, InOp will appear on the display and the engine will have to remain ON for one hour before any more attempts can be made.

Radio-Code.com charges $28.00 and you can retrieve your code online  http://radio-code.com/page3.htm  A Pay-Pal account is required.

the12volt

As for passcode combinations, we will try using numbers from the VIN.  We'll also give GMC a call for more ideas.

Hmmm.... Or....  Call the dealership and get them to call the previous owner (we purchased the car used) for the code.  I also have this feeling that the dealership has purposefully changed the passcode (if that's possible) just to have us return and, you guessed it, pay them more money for the necessary repair (or, in their case, the actual passcode).  However, wouldn't they be required to give us the passcode if they had it?

Thanks, the12volt!  I'll give them a try when all else fails.