Actually, that link is talking about one of the two plants in Millersburg - a few miles SE of Elkhart. FR also has operations in Goshen.
There are 2 plants in Millersburg. One builds bumper pulls - Rockwood, Flagstaff, and Shamrock. The other builds 5th wheels, and may also build other Rockwood/Flagstaff bumper pulls.
We spent a night in Elkhart on a trip this summer and drove by the Roo factory. It was Sat, so no chance for a tour. DW was crushed about that.
Below are a couple pictures. Didn't stop at the other Millersburg plant, there were a lot 5th wheels out in front.