This issue is a variant of Marvel Two-in-One (Marvel, 1974 series) #91 [Direct].
Indicia reads "Marvel Two-In-One Featuring The Thing".
The shadow figure on the cover gives a strong suggestion that Batman may be this issue's guest star.
Letters from Robert Pope, Patrick J. Power, Kurt Friedman, Phil Jones, Stanley Johnson, Marlin Hinter, Dan H. Eiler, Rod Wahowske and Sid Plair.