I have a 1985 Bayliner Capri, and need replacement vertical windshield
support posts...any ideas where I might be able to source these?

Jim

You will find some Bayliner owner's groups in Google.

You will have a dickens of a time trying to find OEM parts for a 20 year old
Bayliner, or for most 20 year old boats, for that matter.

Somebody in the owner's groups might have a source, but be prepared to have
something fabricated in a local $hop.