This issue has variants.
There have been numerous updates and changes to creator credits for this cover. See Change History for details.
On July 13, 2017, Howard Bender contacted the GCD and let us know he specifically remembered Ed Hannigan pencilling this cover during his time working at Marvel. Nick Caputo concurred that it was Hannigan pencils and Cockrum inks.
Bob Bailey got in contact with Ed Hannigan. Ed said it was his layouts, but he could not remember if he did the full pencils or just the layout.
Based on conversation exchange, the credits were updated to Ed Hannigan and Dave Cockrum (without qualifier like layout or finishes on the credits) on the pencils and Dave Cockrum on the inks.
Previously, The Marvel Comics Index (Olshevsky, 1981 series) and Official Index to the Marvel Universe (Jensen et al. 2011) credits were used to give Bob Brown pencils, Dave Cockrum inks, and Annette Kawecki letters credits.
Later, Ron Wilson was suggested as possible pencils but later dismissed as a possibility. After that, Mike Esposito was mentioned as possible inker, but suggestion discarded based on Howard Bender's and Ed Hannigan's memories.
Source for Saladino letters credit is The Marvel Comics Index (Olshevsky 1981).
Letters from Larry Dean, Bob Hobart, Steve Andrews, David Lynch; Marvel Value Stamp Series B #30.