Pretty sure this is later than 68?

[Robert Grant]

The first clue is the 70-channel detent UHF tuner. I haven't seen a set older than about 1973 with this. It was mandated in the US around this time (just like UHF tuners themselves from 30 April 1964). An expansion of the all-channel act required that sets not only be able to receive UHF, but offer equal amenities for UHF tuning as for VHF. In this case, "clickless" UHF tuners that tuned like a radio had to be replaced with ones that clicked (or, in the case of very inexpensive sets, particulary mini-portables, the VHF tuner went "clickless" as well).
A more reaching effect of this was that now, TV sets with remote control (which had only allowed for the remote switching of the VHF channel knob, and thus allowing only one UHF station manually set at the "U" position), had to change between one UHF channel and another as well. The proportion of sets sold with remote control briefly -fell-, until new tuners could be designed, first with several (usually 6) slots for programmable UHF channels in an 18-stop tuner, then the rush to electronic tuning.