The OEM signals are 1156/2156 single filament bulbs (single center contact) and there's no running lights in either end.
If your aftermarket lights are dual filament and everthing's wired up, someone has (tried to) put running lights on it.
Real good chance the aftermarket signals are either Lockhart-Phillips, or use the same bulbs LP's do. At least around here, most m/c shops carry the bulbs, but they are not a standard auto bulb, so you usually can't find them at the local auto parts store like you can with the stockers.
It's actually easy to do the fronts on some of the early 2G bikes as the main harness to the signals has a running light wire already there, it just doesn't have the extra wire on the signal's pigtail. Later bikes don't have the wire in the harness either though, but on US "S" models, there's still a keyed 12v unused wire behind the fairing. (It's there for a running headlamp bulb that mounts dead center in some other markets.)