Here a photo of the parts and the stock numbers for each parts.
The rubber grommet I used last night, I felt it was still a bit big (1/4 inner diameter) after trimming down. It the one on the far left in the photo.
I went back to Lowes today and got two different rubber grommet which have 3/16 inner diameter both center and far right in the photo. I decided to go with the one on the far right because it a little thicker rubber which I think make it easier for me to insert it into the hole in the plastic end cap.
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I use a 5/16 drill bit to drill the hole in the plastic end cap for the rubber grommet which I choose the one on the far right in the photo above (#884624). It come with two in a package also the end cap comes with two in the package.
Photo of the end cap drilled out and sliced with rubber grommet inserted in. Make sure that the slice on end cap and rubber grommet is going in the opposite direction. I plan to use silicone seal covering the slice on the end cap after I inserted it into the hole. But I plan to use only waterproof grease on the rubber itself.
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Here what it look like with cable inserted into it using a different smaller rubber grommet than the one I used yesterday
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