I just did the trim on the back of my 73 vert and had done the short pieces used on a vert A pillar also. I was a tool & die maker for many years. We use to have to bring some of the molds to a mirror finish and used stones and diamond paste to do that job because steel is so hard.
For the aluminum you should not have to sand any unless you have to take out a dent then work the metal back. I would never go any lower than 500 grit, then 1,000 and 1,200 then buff. If the parts are not scratched or have big defects no need to sand at all. I got one of the pedestal buffers at Harbor Freight. You can use a air grinder also. You should have a buffing pad or wheel for each buffing compound that you use and keep the wheel or pad in a zip lock with the compound, never mix them. One piece of coarse grit on a pad or wheel will put scratches back in. So I start with a red compound usually first. CAUTION, IF YOU HAVE NEVER USED A POWER BUFFER YOU MIGHT NOT WANT TO TRY. IT WILL TEAR A PART FROM YOUR HANDS BEFORE YOU CAN BLINK AN EYE. Never wear loose gloves or clothing. People have been killed buffing parts. I was a tooling engineer at National Lock Cabinet Hardware division and we had rows of vibratory finishers, buffers and I do not think there was ever a time we did not have someone with a broke bone in their hand from the buffing line. The thin aluminum will catch very easily if you tip the part too far into the rotation of the wheel. You have to keep the wheel pushing the part and never buff so the wheel is pulling the part. Need to do a video to show cannot tell in words. You need to have several parts to do so you can let them cool they get hot quickly. You have to clean and wash the parts between each grit used or you will never get a good polish.
Once I get what I like on the buffer then I go to the bench and get the micro fiber towels and I like to use old cotton socks. I use the socks to apply the polish compound by hand to do the last finish. I use Blue Magic Metal Polish Creme. and also Zephyr Pro 40. Both say they have materials in them that protect but not for long. After I hand polish applying and rubbing with the sock I buff with mico fiber towel. After everything is done I wash with lacquer thinner and spray with clear lacquer. There are some two part aerosol can sprays out there that will probably last longer than the lacquer but I am 69 and I am not worried about how long it lasts, lol. Zephyr also makes a spray cleaner that removes hard water spots that works called Pro 50 can use on lots of things like windows that get water spots.
99.99% of the people do not get down and look at your polish job on your trim. They walk by at 5 to 10 feet in the bright sun and could not see a place the size of a pencil lead. Only those doing the work ever see the flaws.
Any of the products I have mentioned can be found on Amazon or lots of truck stops carry them because of all the aluminum on the big trucks now.
Be sure you have all the anodizing off or you will be going back to the oven cleaner. It will not polish the anodize.
Not that much of the drip rail is seen so you don't have lots of area. Keep the part moving when buffing so you do not wear low places in the part.
Maybe I should set up and do a video of this because it is confusing and also can be dangerous.
I have about a 5" scar on my left hand & arm where a wire brush on a small side grinder got me earlier this year. I had kevlar glove on that saved me but still took several weeks to heal. Anything spinning at thousands of RPM's is dangerous and if it has a 1/3 - 1/2 hp motor attached it will eat you alive.
Most parts are chemically polish or done on automatic lines today but some hardware still gets hand buff if the volume is low.
BE CAREFUL.
