Here are some numbers I posted a while back when doing the 2 speed to 3 speed swap.

Here is a update. I looked in my 69 parts manual and this is what i found.

1-The dash wiring is the same all engines all wiper systems. This is for 69-b-body models.

2- Wiper motor 2 speed-2770090
3 speed 2983116

3-wiper link 2 speed 2631799
3 speed 2822273

4-Bushing 2 speed 2631766
3 speed 2580200

5-Switch 2 speed 3004177
3 speed 2864014

The rest of the linkage ect is all the same.