Applause (Ovation) AE-40 Acoustic Bass Guitar Questions

I have an Applause AE-40 bass guitar I bought back in the '80s, and I'm curious about it. I don't know the year, and it has a rare feature that I've never seen anywhere else. Rather than the 4x4 headstock key arrangement they usually have, it has the inline, Fender-style arrangement. I was told that this is the first year, and that the company decided to go with the 4x4 keys after the first batch.

The serial number is 216xxx. Can anyone help me with info about this series and this particular one?

Thanks.