In 1974-1975 five months before the release of the anime Gamba no Bouken there was a newspaper “Yomiuri Shimbun” that published a version of the novel 冒険者たち ガンバと15ひきの仲間 (The Adventurers: Gamba and His Fifteen Companions) by Atsuo Saitoh.

Because the animation rights were sold to another studio it was canceled after only 7 numbers. https://twitter.com/mtsujiji/status/1519926401368948736

日曜版のシナリオを書いていた辻です。原作者と意気投合しながらだったのに、肝心の映像化権はわれわれの頭越しにもう売られていたと判り、われわれの企画は立ち消えになりました。これが「大人の事情」です。

Colored version are samples from mandarake and additional info from there:

[Comment] Adapted children's literature by Atsuo Saito for newspaper serialization.
Adaptation: Masaki Tsuji + Illustration: Shoji Ikehara, Tadanao Tsuji

【コメント】斎藤惇夫による児童文学を新聞連載用に脚色。
脚色:辻真先+イラスト:池原昭治・辻忠直
連載第一回挿絵用原画
昭和49年12月1日読売新聞掲載欄切り抜き付

Scans from
https://twitter.com/nfuJDsUmIJ0LEbd/status/1519683818541633537
https://twitter.com/nfuJDsUmIJ0LEbd/status/1520048599232524288
https://twitter.com/nfuJDsUmIJ0LEbd/status/1520055137074434050