I took Chuck Eddy to task for calling "The Night Chicago Died" rap quite a while ago, and he has now responded, belatedly but good-naturedly. Here's Chuck's defense:
The rap part of "The Night Chicago Died" is the INTRO, dude: "Daddy was a cop/On the East Side of Chicago/Back in the U.S.A./Back in the bad old days." Go back and listen again; you'll see what I mean.
As for "Walk This Way," Run DMC covered that song because Rick Rubin read a Village Voice review of Done With Mirrors I'd written in which I called "Walk This Way" rap. 22 years ago! You can look it up. (I called "Lord of the Thighs" rap, too, but nobody ever covered that one.)
The "Night Chicago Died" intro isn't really sung, and it's not spoken-word, so I guess you would have to call it proto-rap. Here, you be the judge: