I posted once before on replacement locks I just had the keys to my Cuda stolen in a breakin. I immediately ordered a new lock set from one of the restoration companies. Just for grins, I tried the existing key similar to the stolen key in the locks. It did not work in the door locks but it immediately opened the steering wheel ignition lock. I also tried two other old Mopar keys and they opened the ignition too.
Does anyone make a more secure ignition lock? Seems like just about any key that fits in the slot will open the lock. The locks made by Standard available at Oreilly's are just as bad.
Picture is the new cylinder and some of the keys that open it.
Craig

Your ignition lock may not have all its pins which makes it easier for multiple keys to open it.

What he said. Sounds like you need a new lock cylinder or the column is broke.

I do not know of a more secure lock but get a club or removable steering wheel with a lock plate. The goal being to make it more difficult to steal. They also have these things that car called steering column lock. Covers the lock and wraps around the column.

Take the lock to a locksmith and tell him you want all 5 tumblers. Most likely there is only 1 or two in there.