Replaced the trap, front bearing assemblies and slides since I had to pull the machine apart anyway. The dryer model I have uses all four slides (two of the white and two of the gray). I only ordered two of the white as per recommendation. I'd suggest replacing all four but didn't want to wait a week for the additional two. The duct trap assembly is pretty stiff and can be a bit of a bear to fit. I suggest warming the piece using a heat gun or allowing it to sit in the sun to make it a bit more pliable. Removing the front and laying it flat on a blanket makes the job much easier.