One of the authors I have been reading over the past couple of years maybe 3 or 4 actually) really has a good grasp on the various AD&D character classes in my opinion.
A. Lee Martinez writes stories that , to me, almost always seem to include at least one character that really fits the description of an AD&D class like a magic User or an Illusionist, a Fighter, etc...
Obviously, his characters aren't complete, blatant rip offs of the classes, but I think they are so darn close in some aspects that it's certain to me that he is or was an AD&D gamer.
For example, in the book "A Nameless Witch" he introduces a pretty typical Magic User as the Witch (who is also un-dead) and pits her against a character he refers to as a "Wizard" but almost exactly fits the description of an AD&D Illusionist. A very high level Illusionist at that.
Not only that, but the same book includes as one of the witch's allies a character that is pretty much the description of an AD&D Paladin. Well, the character operates very much like a Paladin anyway.
Just about all of Martinez's books seem to include at least one or more characters that fit an AD&D Class mold. It's been a lot of fun to read them just to see how he implements the classes in stories like his which fall into the "fantasy fiction with a humor and wit" category I think.