You just need to have the appopriate ing. harness I believe. Wait not the harness, just the the actual switch is different, and that plugs into the harness.
I know a '68 dash harness has a different style connector for the column (square 2? row instead of flat 1 row) because it only has turn signals instead of ing, turn and hazard like the '70+ do.
Basically the differences are key in the dash and hazard switch in the dash.
The '69 ignition key cylinder is a 1-year only design and very hard to find. I believe there are conversion kits to allow the use of more easily found '68 key cylinder.
The '69 ignition key cylinder is a 1-year only design and very hard to find. I believe there are conversion kits to allow the use of more easily found '68 key cylinder.