FS doesn't really have any industrial landclass per se. I normally use Large City HiRise (#121) and place factories and other such buildings on top of any resulting autogen skyscrapers (which suppress them).
If you have ORBX FTX Global and OpenLC, there are a couple of good industrial land classes included. You have to make some changes to the "shapePolyList.dat" file in ADE to use them, but it's not particularly difficult. I attached a couple of thumbnails.