A massive updated suit of armor from the original suit in which Tony Stark introduced hot rod red in the trademark color sceme.  The Golden Avenger first appeared in Tales of Suspense #48.  This armor is what set the standards of todays armor Tony builds.

Tony Stark in the armor's first appearance in the Silver Age:


Source: http://marvel.wikia.com/wiki/Tales_of_Suspense_Vol_1_48

Iron Man in his own magazine apart from Captain America:
Source: http://iconicauctions.com/stan_lee_signed_original_1968__the_invincible_iron-lot36548.aspx