Good luck dealing with Happi Jac
You might try to see if you can get the stuff you need from Walts RV salvage in Fontana.
Its basically a RV junkyard, a friend got most of the stuff needed to convert an old hauler without a rear bed. NOT the best customer service, they are going to point you to the area where the bed stuff is and your going to dig thru the stuff until you find what you need or give up.
I know they had a bunch or tracks and the pieces that crawl up and down the tracks, but not sure about anything else. If your the type that has some fabrication skills this might be the answer
Good Luck
2008 GMC 2500HD 4X4 DMAX CC
2004 Thor Wanderer Wagon 247WTB
2006 TE450 Husky
2007 Rhino Sport Edition