My vent windows are whistling in the wind. Is there a way to replace the little plastic piece at the end of the locking handles with some that are slightly thicker. That should stop the air leak.

A company called LMC truck(1-800-222-5664) has the complete handle available for $30.00. jeffs bronco graveyard might have them also, they would definately would have used ones for less$. My '62 Falcon was doing that also. It got so irritating that I used some sillicon(not perfect but real cheap) to lightly seal it, still works to this day.

dennis carpenter manufactures the latch.you can cheat it all by putting a nickle in between the latch and vent window.<br>dennis carpenter.com

Snow too if  you had the heater maxed and still liked the fresh air coming in. My 65 Impala SS had vent windows and occasionally would give me a blast of snow if the wind outside hit just right.