Jerry Grandenetti pencil credit added by Mark Evanier (via the GCD Errors list, August 2009), who credits him with about half of the story.
Nick Caputo adds that Bill Everett may have penciled and inked most of the first two pages, with Grandenetti doing the rest (over Kirby layouts?) with the Hulk and Rick Jones apparently inked by Everett throughout the story to maintain consistency. Other inkers likely include Mike Esposito, Sol Brodsky and John Tartaglione. Panels 1-2 on page 5 are reproduced from Sub-Mariner story.
Previous indexer credited Paul Reinman and John Romita with inks.
Cross-over with Sub-Mariner.