there has been lots of speculation, basically the story I got was he hurt his back and had lots of downtime, so he started doing work around the digger shop. and in turn did such a good job he is kinda of needed more as a fabricator then a driver.
Chassis's he has built to date are:
monster energy
GD the legend
SUD
GD 19, 20, 25
crusader
tasmanian devil/grinder
wolverine
capt curse (the one blackwell drove after he wrecked it at WF's two year ago)
both 3 seater chassis's