bolt in sub frame connectors

I don't believe there is any difference between 67 and 68...and if there was it would have been extremely minor.

The Barracuda is 108" wheelbase so you need connectors for that.

I'd highly suggest you went with some weld-on types. You are bolting through hollow members. Unless it comes with sleeves, which I am not aware of, it will eventually either crush the metal or come loose.
I would NOT sweat crushing the metal subframe, EVER!
BUT. Surely weld them in when the chance comes up.
...is this a quarter mile car?..are you sure you need them?
Every person I have ever crossed that has installed sub frame rails has always said the most positive things. Needed or not, it is a win win. Unless your doing a OE resto, then you get points off. #-o