In West Karana: He's in the guard tower south of the Qeynos Hills zoneline.
You say, 'Hail, Guard Donlan'
Guard Donlan says 'Welcome, traveler. Have I informed you about the (travel tax)?'
You say, 'travel tax'
Guard Donlan says 'The travel tax is a fee of one gold for the privilege of using the highways of Karana. Oh! You know what? You must've used the roads to get here! I guess you owe me 1 gold!'
In the Ethernere Tainted West Karana: Known spawn locations (click for map image -- PH "a traitorous guard") for your "ethernere.txt" map file (note for all known Ethernere Tainted West Karana named spawn locations, see this quest entry):