If Frank Sinatra had played Harry Callahan

... as he had been scheduled to do prior to suffering a hand injury in November 1970, I think that Dirty Harry (then set to be directed by Irvin Kershner with a rather different script) would have been more akin to The Dead Pool (Buddy Van Horn, 1988). An older, curmudgeonly, grumbling cop pursues a psychotic killer in a lightly entertaining, rather parodic affair that makes a few clever comments but doesn't offer much punch or heat. Indeed, in The Dead Pool, an aging, mellowing Harry actually starts dating a blonde! Certainly, he isn't the misanthropic, iconoclastic Harry of old, and the film becomes a routine (if occasionally funny) Hollywood cop movie, lacking the rebellious fury and distinction of its series predecessors.

http://www.the-dirtiest.com/sinatra.htm