I'm getting ready to repaint my new to the truck tailgate, and I noticed how bad the aluminum panel looks. I've tried Mother's chrome polish with a buffer, but it didn't seem to help out much. Anyone have any ideas on how to make it look any better?

 

You'd have to remove the clearcoat first, then shine the Aluminum (don't use Chrome polish), then re-apply a clearcoat. Search for threads about polishing old Aluminum wheels.

 

What I would do, is take soapy water, and 00 Steel wool, and carefully "wet sand" the panel. Being super careful to only go left to right (do NOT go up/down) If you'd rather use a sanding block or even a sponge as a backer, use 1000 grit, soak it in water 24 hours, then use that and a spray bottle of soapy water. keeping the area wet and apply light-moderate pressure. Be slow, and methodical as any stray that's not left to right will show up. Once the entire tailgate is done, then you can clean it, wipe it down with acetone, then do a coat of clear on it to seal it. Hope this helps. I should point out, do this on the metal portion. Not the plastic. You can use a good headlight polish on the plastic section if its faded.