I was wondering if anyone has changed the ignition switch on the steering column of a 240Z. The real question is about the mounting bolts. There are 4 bolts, two with a philips head and two that are just with rounded tops (making them impossible to remove). On closer inspection the rounded top ones do appear to be threaded. I need to remove these and was wondering is there a special tool I need or does someone have a suggestion other than drilling them out. I would appreciate any suggestions you may have.