[unruhjonny]

I just refreshed my memory on the precise application of the "1970" wiper switch.

I did this because I thought I had a spare switch that a member here was looking for (it turns out my spares are NOT what he wants).

Over simplified:
1970-1972 = black switch with "WASH" in white print
1973+ = chrome push button with black in background to make the word "PUSH" appear in chrome

I am seeing in my "go-to" MPC (1975 model year) that there are different numbers for:
1) 70-72 with recessed wipers; 1994089
2) 70-72 w/o recessed wipers; 1994090
3) 73 EXC A/C; 1974-ALL; 1994193
4) 73 WITH A/C; 1994145
5) 1975 with recessed wipers; 1994179
6) 1975 w/o recessed wipers; 1994178

I had mistakenly thought that there was one switch that covered all...

I would assume that over time the 70-72 part was replaced with a suitable later part - and that much quicker than this, there was a consolidation of the 73-75 parts.

I have attached images of NOS 1994090, and NOS 1994089;
It looks like the difference between the two is that the lower left connector on the 089 (recessed wiper) is a ground(?) which has an added piece which allows it to ground out in another spot?

Can anyone help to understand the part number differences, and which ones interchange?

EDIT:
The spare I have in hand here is a '178 - this has that same ground(?) as the '089 - except the '089 is for cars WITH recessed wipers, while the '178 is for cars w/o recessed wipers.
THe last three digits of the part number are stamped on the back of the large mounting tab on the top of the switch.
Super confused.