security ? on 99 sub

[kev63rod]

hey i bought a 99 sub with the 5.7 in it for really cheap but the guy had lost the keys and drilled the ignition. drove it with any key for a few weeks then decided to try an old ignition that i had out of a 97 van. well the security light was on because im sure it didnt like the key/ignition setup but it started several times and ran for several minutes like that so i thought problem fixed. next day it was start and die right away. so now im looking at buying a used column and key but was wondering if that will fix it or will i be forced to take it to the dealer and have the BCM reprogramed for the new key/column setup. the 97 ignition i used did not have the little black chip that sits against the ignition and has 2 wires going to it. (yellow and orange iirc) im wondering how the thing ran all that time with any old key and never had the security light on?