JOURNEY INTO MYSTERY #101 was the 15th and final comic with a Thor appearance to hit the spinner racks in 1963. There was a 13 page lead story guest starring the Avengers, plus a 5 page "Boyhood of Thor" back-up story. Both were drawn by Jack Kirby and George Roussos.
I was buying comics back then but instead of that I chose to buy this
If only they had put young Thor on the cover, given him a dog and had Curt Swan draw it, maybe I wouldn't have waited 3 years before I bought my first Thor comic.