The low frequency drivers are probably 6.5" so they are AR 226PS speakers. I don't know where you can find replacements for the 1" polycarbonate horn-loaded tweeter.

Hi, I have a couple of pairs of old AR90's I'm going to restore and have shopped a little for parts.

Here are the most comprehensive sites I have found...

AB Tech

Regnar

One note of caution. I have been told that some of these replacement parts aren't fully to original factory spec, so they may or may not match well with your application.

I emailed AB Tech regarding trying to buy some parts, but have never heard back. I'm not sure if they are very active/viable, but they're worth a call.

Lastly, AR is now owned by Audiovax, so www.audiovox.com may be worth an email to check availability.

Best wishes.