The Wedding of Bobby Hill - S3-E14
Revealing mistake: During Rad's haircut from Luanne, there is a shot that shows the both of them in the mirror. You can see both their reflections and the room in the mirror but the objects on the counter in front of Rad have no reflection.
Answer: Jeffrey Boomhauer is a Texas Ranger as can be seen in the final episode at the end when he sets his wallet down, it flips open revealing a Texas Ranger badge.