I did start out with the sanding first to remove the casting and get the the bare aluminum. Although I have found that if you start out with 100 grit then work your way up is the better route. When I started with 80 grit it took forever to remove the deep scratches. But before the sanding I would use the dremel with the alum. grinding stone #8175 and the carbon steel wheel #428 to prep it for the sanding. Let the dremel do most of the hard work for you. After you have done that then start sanding with the 100 grit and work your way up to 150, 180, 320, 400, 600. Then comes the good part. I used the dremel with the polishing wheel and first applied the tripoli compound and then the white rouge which can be purchased from
www.eastwoodcompany.com
The final step was to apply a metal polish to protect the part from rust. I know it's alot of work but take your time and start with a small part first. But let me warn you, once you start it's hard to stop because it looks sooo damn good.
I will try and post a picture or link of my altenator in the 400 grit stage. and a before and after of the air conditioning unit
If anything is unclear let me know.
89lxstang