I'm wondering what year Chevy started with the rounded valet key in addition to the hex-shaped ignition key? One key works all the locks on my '58. Should it have a valet key too or was that feature added later?
Thanks folks.

The 1948-1963 used the single key. For valet parking the key could be removed in the unlocked position and the car driven with no key and the trunk locked.
As far as I know the 1934-1947 and 1964 and up had the round trunk key.