The closed spoke 999 steam engine is probably more rare than the open spoke version. It seems that when Marx experienced breakage problems with the open spoke 999 they altered the tooling to fill the back of the pilot, leaving the spokes still in place. They must have encountered production problems with this version because they seem to have changed the tooling again, rapidly, to eliminate the spoked pilot all together!



This view shows the pilot. Notice that the area between the spokes is filled rather than open.