Brakes Brake fluid reservoir replacement

This is my original still in the car and the part I received today.
The

Prob return the NOS part and just leave this alone!
Thanks for your help 5L5, info and photos! Very helpful!

Mustang5L5 said:

I actually think it won’t work. I think NPD is wrong in this case on the part application.

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I can see myself opening a can of worms just because I want a clean reservoir. It’s Not worth it. You convinced me. I’m Sending both back, the NOS and replacement part (I have both) and leaving this alone! If I decide to re-visit this idea in the future I will just change the whole MC and not play with just the reservoir.
I’m my own worse enemy sometimes. It works fine just wanted it clean but I think this will end up kicking me in the a$$.
Ok, Thanks for talking this out 5L5!