I bought a new ignition lock/door lock set. I pulled out the old ignition lock out of column. It pulled right out so nothing seemed to be holding it in. The original has a spring loaded pin on it, but apparently it wasn't going in a retaining slot. New lock doesn't have a pin, it has a spring loaded c-clip? Did design change or do I have the wrong lock?

C type spring loaded is for 70.
Pin type is for 71-74.
the C type should work on 71-74.
Be carefull, some pin type locks will not work on 71-74 collars as the hole is not in the same position as the
replacement pin on the lock.
Check to see if your steering column lock collar has a groove on the inside. If it does you can use the C type lock.
Jules

Thanks Jules. Its a 70 Challenger. Old lock had a pin, but wasn't being held in by anything. Just pulled it right out. Ignition keys wouldn't unlock doors, so hoping it was just replaced with the wrong lock. Any trick to get the clip in the groove?

Just hold the C clip down while you slide the lock in the chamber of the collar.
It will engage by itself.
If you need to remove it you will notice a small hole inside on top of the chamber.
With a thin rod or precision screwdriver you can push down on the C clip and slide the lock out.
Jules