I have a wiper motor that has part number 3431532 on it that would indicate it is a 72 A-body variable speed wiper motor. The date code on it though is 2141 which I believe is June 8, 1967. Has anyone else encountered part and date code numbers like these that don't match up?

That date looks like the 214th day of 1971 to me.

I was going by the 10,000 day calendar. Is the 10,000 day calendar only for car production dates and not parts?

Vendors used their own date code system for the most part. Maybe a few of them used the Chrysler date code system. I don't know of any fixed "rules". You just have to figure it out as you go. The GG books are the best place to start.

It varies by the component, not a standardized one size fits all for every part, for example I believe engine blocks were dated by a 10,000 day calendar at least for castings.
But dates on other components have different formats which were likely dependent on what supplier was used. Wiper motors were typically 4 digits being the day of of the 365 day year and one digit for year.

Agree with AndyF. Wiper motors typically have the 4 digit date code with a 3-digit number of days (001-365) plus single last digit of the year.

I just learned something new. Thanks guys.

Big blocks have the actual date cast on the side and the actual date stamped on the ID pad. Small block engines use the actual date on the side but then use the 10,000 day on the assembly stamp. I'm not really up on what other engines used. The FSM and the GG book cover some of this. The master parts book also has some info. Other than that you just have to scratch around and see what you can find or figure out.

You can get a general overview of some of the various vendor date code types used at https://www.hamtramck-historical.com/dateCodes101.shtml