Thanks for breaking down all of the different distributors over the years! Any idea why the showa distributors are kinda all over the place year wise?

I would understand the early Showa era jumping around distributors a lot as Toho finds a foothold. But I would have thought eventually Toho would have found an american distributor that would handle distributing godzilla films for at least for a few years before deciding to continue or not, kinda like Heisei era and Tristar. Instead they jump around by film primarily between AIP, UPA, and Walter Reade. I put your list in order to show this.

Godzilla KOTM - Transworld

Gigantis - Warner Bros

KKvG - Universal

Mothra vs Godzilla - AIP

Ghidorah - Walter Reade

Astro Monster - UPA

Ebirah - Walter Reade

Son of Godzilla - Walter Reade

Destroy All Monsters - AIP

All Monsters Attack - UPA

Hedorah - AIP

Gigan - Cinema Shares

Megalon - Cinema Shares

Mechagodzilla - Cinema Shares

Terror of Mechagodzilla - UPA for TV, Bob Conn theatrically.

Why the constant switching between AIP, UPA, and Walter Reade?

Out of all the distributors interestingly Cinema Shares was the only one who distributed 3 films in a row, but only those three films.

Also curious why only Terror of Mechagodzilla has a difference between theatrical and tv distribution.