Wiper Motor Question? 68 Charger

A friend of mine is installing a 3 speed windshield wiper motor in his 68 Charger.
When doing this swap, is it manditory to also change the "arms" to the 3 speed ones.
Been getting different answers to this question.
Anyone know with 100% certainty.
Anyone personally do this swap in the past?
Thank's in advance.

Ok. Lets call them the "linkage rods" that connect to the wiper motor in the cowling.

which arms? the wiper arms?
no

No , not on a 68. All the arms and pivots are the same. Just need the motor, with the plastic cam bushing and the switch.

I did it back 20 odd years ago when I added an airgrabber to a 69 GTX. The motor was a direct swap. Believe it or not the 2 speed switch will still work with the 3 speed motor. I waited till the dash needed to come out anyway to change the switch!