Differences between 1968/69 and 1970 Rallye Woodgrain Steering Wheel

Hi, Haven't found a thread about this.
I'd like to know if I can install a 1970 Woodgrain Rallye Steering Wheel on a 68 Barracuda.
I know this:
-1970 has small holes on the spokes
-In 1970 the color of the woodgrain is lighter
Questions:
-Is the horn adapter different on a 1970? Do I have to find a 68/69 or it will work anyway?
-Will the spokes holes be visible then?

Thank you