Ken, You can figure this out with a little experimentation. If the wires are coming from the headlight switch side, get a test light or a meter and move the switch to different positions to see what wire lights up and when.
If the wire is coming from the bulb side, run a jumper wire ( a long wire with an alligator clip on each end ) from the hot side of the battery and hook it to one wire at a time. If the parking light lights up obviously you have found the parking light wire. If nothing lights up you may have a bad bulb or a bad ground in the fixture. Wiring diagrams are nice but a little patience and experimentation works as well. I hope this helps out.
