Aluminum MLC
As with clips this is a very common mix of 1100, 3003, 3004, 5005, 5052, 6061 and 6063. Unlike clips, MLC is usually the thick solids instead of the thin clean sheets. MLC is the initals for mixed low copper

I am sure it is the same as what you are getting as sheet.
By me only catagories are Rims, Ext, Alum cans, MLC, Paint, Cast, Dirty and transmissions/alum motor