It is possible to get a pretty good idea of an adult kingsnake's sex by looking at the tail, especially from the belly. Its kind of subtle, but can be fairly accurate, at least in my experience.
A female's tail tends to taper quickly from the vent. A male's tale will usually taper slightly, then show a buldge almost as thick as the end of the trunk. After the buldge, the tail will taper, but not as sharply as a female's, and the male's tail will be longer overall.
The key is experience - it helps to have seen and compared a few male and female snakes of approximately the same size. Unless you plan on breeding, the snake's sex is irrelevant. If you do plan on breeding, get a set of probes and learn to use them - you're gonna need to anyway!
Good Luck and Post some Pics!
John D
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I am so not lesdysxic!
0.1 Creamsicle Cornsake "Yolanda"
1.0 Bairds Ratsnake "Steely Dan"
0.1 Desert Kingsnake "FATTY"