Some marvelous person uploaded this gem - the 1972 team's audio highlight reel, narrated by the late Steve Gilmartin. Along with being a fascinating insight into that tremendous season, it got me searching for similar content but it's a bit hard to come by. Apart from this reel, produced 10 years later, I can't seem to find any local radio broadcasts of games outside of the excerpts used for NFL Films highlights.
Surely there's got to be a cache of radio highlights or play-by-play for this franchise - I'm sure someone kept their tapes of Sonny, Sam, and Frank calling some of the best moments of D.C. sports history.