What year did the front seat have a latch which had to be used to get into the rear seat? Was it 67 or 68? I know 69 has it.
All 3 years.
What year did the latch become standard?
It was never optional.
I found this... It appears some manufacturers started incorporating them prior to the mandate.
Federal Motor Vehicle Safety Standard 207, which took effect for passenger cars on January 1, 1968, is one of the National Highway Traffic Safety Administration's initial vehicle regulations. It specifies strength requirements for automotive seats and their attachment assemblies, so as to "minimize the possibility of their failure by forces acting on them as a result of vehicle impact." Many of the specific requirements of Standard 207 are based on the Society of Automotive Engineers' Recommended Practice 0879, which had already been in place since November 1963. The one significant difference between Standard 207 and Recommended Practice J879 - the one tangible modification of vehicle seating systems in model years 1967-68 - was the introduction of seat-back locks in the folding front seatbacks of passenger cars with two doors.
Perhaps the jackwag who designed the bottom seat security bracket for the 67-69 Camaro took this a little too seriously.