Google wins again...

Here are some pics of a '67 seat:
pic1
pic2

As to which latching method works better:
"The clips in the upper corner are just tension grip and would let the seat flop forward on hard breaking. That's why the latch's were changed to be a positive hook."

BTW,

Here is a pic showing what the chrome tab on a 67' back looks like. It is the part that slides into the keeper:
chrometab