OMC is out of business. I would question parts availability.
And more importantly service availability.

Most parts are still available. Some are non existant. Service is
still available.Drives can still be rebuilt.
Manuals are available that cover all OMC drives from 65 to end of
production.
I know a few old gear heads that are wizards with OMC. I'm still using
a 65 OMC drive that runs flawlessly.You DO have to know WHAT you're
doing to work with them.