From memory (I had to change the blub in the alert), the speed alert unit should clip in or you have to screw it from behind. But you have to take off the dash (don't forget the to take out the two screws face down in the speedo area, and then that part of the dash should clip off). Also you might have to disconnect the HZ, AC, Rem.Dim connectors from behind those switches so that you can take it off completely. But as fitzy2005 said, make sure you have the connector.