I don't know much about W. Glenn Duncan except that he wrote a dandy private-eye series set in Dallas, Texas, while he was living in Australia. The Rafferty books were published in the late 1980s by Gold Medal, and I think of them as throwbacks to the kind of p.i. books GM was doing in the '50s, except influenced as much by Robert B. Parker as by Spillane.
All the Rafferty books are entertaining. I just picked this one because I ran across a copy the other day. As you can see on the cover, Rafferty has a double caseload. He's used as a pawn in a murder plot, and he's looking for the guy who tricked him. At the same time, he's trying to help out a geezer who wants to keep some kids off his lawn. Really. (Okay, there's more to it than that, but I like the image.)
Rafferty has an on-going relationship with a woman named Helen, who's much more interesting than, say, Susan Silverman. He also has a psycho sidekick named Cowboy. Even better, Cowboy has a psycho sidekick, his wife, Mimi, who stand about four feet tall. Here's how Mimi's introduced on page 112:
The 9mm Beretta she'd been concealing behind her hat went into a holster on her right hip. . . .
Mimi nodded and opened her jacket. She had an Uzi slung under her right arm. . . .
Mimi giggled and scratched her forearms where the throwing knife sheaths chafed her skin.
You don't want to mess with Mimi. But you do want to read these books, right? I get the feeling that Harry Hunsicker's Lee Henry Oswald is Rafferty's direct descendant, though much more modern. If you haven't read Hunsicker, try him, too.