Looks like the lock hole has been cut out. Should be smaller with a couple square index notches.
He was told the exact same thing over on For Road Runners Only. Guess he did not like the answer and came here looking for a different result... It doesn't work that way...
Where is the gasket ?? Might help...... If original doesn't work because the hole is too big go shopping @ local hardware or Lowes to find a oversize flex washer.. ACE / ACO hardware has a lot of selections.
The new one looks correct. Your old one looks to be the 73 and up unit which is larger than the 72 and older one.
Looks like the lock hole has been cut out. Should be smaller with a couple square index notches.
It is sad that when we get these old car's that someone else took a short cut to fix a problem in steed of doing the job rite. But that is how it is sometimes. So make's it rough on the new owner to figure out what part to get if not the original one. But that is why we need a group of guy's on our side to help us because they have been their and done that.