IRON MAN #21 
(Jan., 1970) "The Replacement." 

Cover art: George Tuska.  
Script: Archie Goodwin. 
Art: George Tuska/Joe Gaudioso.  

Tony finally decides to hand off the mantle of Iron Man. His choice: Eddie March, a prize-fighter with a heart of iron...and a secret to go with it. That secret leaves the new Iron Man on the ropes on his very first mission against the new Crimson Dynamo! Nice boxing action scenes by Tuska.

xkot's Recommendation: 4 repulsors!