Actually Nigel builds his own chassis here is a quote from the la supertux website (his company)
"The chassis that are built by Dan Patrick in the USA are acknowledged as the “Industry Standard” with well over 70 chassis now having been built.
It is our ambition to become the “Patrick Enterprises” of the European monster truck industry, and we're not off to a bad start.
LA Supertrux Ltd chassis won the European Monster Truck Racing Championships in 2003, 2005, 2006 & 2009.
Built using CDS with 50mm O.D. and 3.2mm wall tubing, all bends are CNC bent on a mandrel bender to guarantee section stability in the wall of the tube at the bending moment. All LAS chassis are built in a hollow section Jig to ensure accuracy and alignment."