I brought one for my 02 bike, it was identical.
Not that I didn't believe you, but I tend to want to verify that sort of thing myself. Fortunately, I'm in a position to do so. Turns out they're practically but not literally identical - at least not in as-last-supplied condition.
I happen to own what I believe is one of the last supplied 90065-MCZ-640s. I also was able to order a 90065-KR3-000 from my friendly local dealer.
As you can see, the two rods are the same length.
Here's the comparison with the 90065-KR3-000 out of its package.
And with them both out of their packages:
90065-MCZ-640 is on top, 90065-KR3-000 on bottom. Looks like the MCZ has a brighter chrome finish, but wasn't polished (or at least, not much) so it's more of a matte. The KR3 has a darker chrome finish but it's been fully polished and is quite smooth. Otherwise they appear identical.
No idea why Honda hasn't just officially superceded the part from the MCZ part to the KR3 off the later 919s (and the CMX250).