Wiper motor attachment to linkage

I found in my 73 parts book that the crank arm part number has two different part numbers. Vehicles built before 1 Nov 72 the part number was PN 343 1675 for the arm and after 1 Nov it was 343 1741. Mine can off the line in September 72.

I don't know what the reason for the change was other than using up 72 parts.
It calls for 2 speed wiper bushings PN 343 1684.

When the garage warms up enough, I'll try and stick my head up under the dash to see what has happened.