This guy used them on his Pack Mule build:
http://www.expeditionportal.com/forum/threads/113435-1988-Packmule-expedition-conversion
IIRC you can tie them together with some square tubing for some extra rigidity. Been on the fence about using them on my HF trailer frame based adventure box thing, the price is holding me back.
Yep, Just got back from doing the El Camino del Diablo trail between Yuma and Ajo Arizona. A long trail of rocks, ruts, washboard and sand along with a 1,500 mile round trip tow. Suspension held up great throughout the journey and the water tank the axle-less suspension let me put in came in very handy in the desert. Still very satisfied with the Timbren.
at Tinajas Altas (high tanks) along the route.