Theftlock radio unlock with 6 digit code instead of 4 digit.

[spongebob218]

97 Astro with theftlock. Radio displays loc. Got the 6 digit number out of the radio and called the GM unlock 1800 number. Entered the info and was given a 6 digit unlock code instead of a 4 digit.

Anyone know how to enter this? I can find no info online for entering a 6 digit code. All info I found was for a 4 digit code. Thanks in advance for any help.