What do you mean by a "MIDI sync port"? A standard MIDI port will carry all the timing/clock signals, no need for a separate port specifically for the sync data. If you're after analog DIN-sync (as on Roland drum machines, etc.) or tape/click sync, then yes, there were plenty.

I am talking about the wikipedia description of the MPU-401. I don't know what Sync was used for. https://en.wikipedia.org/wiki/MPU-401

There's the problem - that's not a MIDI port at all; even though wikipedia calls it "MIDI SYNC", it is wrong. It's a Roland DIN-sync output, 24 pulses per quarter note, all analog signal. It's the same sync method that's used on e.g. Roland TR-808s or TB-303s.

K, I once made a list of Roland drum machines that had MIDI Sync connectors for the fun of it. The wikipedia gives the pinout of the Sync DIN rather readily now https://en.wikipedia.org/wiki/DIN_sync

What I would really wish of this thread is

1) some sort of shot of a MPU-401 with the sync DIN cable
2) pinouts of MIDI In and MIDI out

Then I'd stare and wonder if any pin of Sync ever was placed on an In?