[Hey Louie]

Dave W hit it on the head. Plan it out and think it thru several times. With the help of a friend we just installed 5 on my Alpine. I was fortunate that the awning rails were already mounted. It took us right about 5 hours to get them all on. We did not have to do any predrilling but it was helpful to have an impact driver for the screws that went thru the mounting plate into the rods on the end of the toppers.

Etrailer has several good videos showing the procedure.