Looking around, there are at least three variations. Reproductions were made by Flat 4 and Vintage Speed. I like the Vintage Speed version the best.
The original had some weird clamps and the slats have their butt-ends exposed.
Racks that have the slats running lengthways will be quieter. Mine hums from 35-45mph.
Edit:
The one made in Spain, the Airstreme, is neat. It has fold-down end racks.
