Ford - Mustang :: 1989 GT Starts Without Key

I noticed something strange the other day that my 89 GT can be started without the key ! Everything works as it should but you do not have to put the key in the ignition lock switch. I did have the ignition switch replaced many years ago when Ford had the recall due to a possible fire.. I believe the switch that was replaced is located down under the base of the steering column and activated with a rod from the column key lock.. Is it hard to replace this column lock switch ?

I would rather do it myself instead of paying a locksmith to do it..I do have an anti-start security system on it and when you enable it it locks out the ignition. To start it you have to enter a certain 5 number code for it to crank. I had this car since new and only 117k on the clock and runs like new. Where can I obtain a replacement "key lock assembly " ? This is the original key lock on the column..Just worn out I guess . Only thing I replaced on this car was a new clutch due to a bad throw out bearing making noise at 80k and a water pump and serpentine belt at 90k and a noisy fuel pump. Still has the original prone to failure ignition control module.