I used to keep sound clips of all the different Mac chimes since Apple would update them every generation or so. I'm pretty sure I still have them buried in a backup folder somewhere, but yes, I can say with reasonable confidence that the current chime has been unchanged since the late 1990s with the introduction of the G3.
I actually liked the sound of the previous generation in the mid 90s slightly better because it had a slightly higher pitch and (I think) had a slight stereo reverb.
edit: Wow, I found my backup folder, last touched in 2007. All of these clips are old Apple AIFFs. I'll convert to something modern and throw up a link to share just for kicks.
edit2: Here ya' go:
https://www.dropbox.com/sh/5rf1mqa19...EnkxeC-Ta?dl=0