Serial #'s

Anyone know when a moog model D with a serial # in the 2000’s would have been built ?

What if anything is specific to those models with 2000 serial #'s ?
Thanks

If it isn’t upgraded, it would feature the “old oscillator”. Probably around '73 or so? If you can look under the hood, there should be some inspection tags inside, and you can see if it has been upgraded.