As always with manufacturer the so called new improved aluminum lower housing was a cost reduction. It was a failure because the threaded portion at the top would not hold up over time while the steel version would last forever.
I have never seen one with a red handle. My best guess is a user painted it red because it was his favorite tool to use on the job. It isn't uncommon for that to happen in a company that has a fleet of the same type of tool for workers to pick from. It is also possible that the tool was made for a certain application, and Ramset painted red for a similar reason.
