I'm glad to see a dedicated thread on this.
As for the Roadtrek picture, Roadtrek offers a Quigley converted van. I'm not sure if Quigley uses Fabtech suspension parts or if the owner of that van added hardware.
I was under my van this weekend. It is a 2005 Chevy Express 1500 AWD and here are the numbers I pulled off of the torsion bars:
Right (orange) - 2LK 484, R 720, P/N 15750720
Left (blue) - 2NE 075, L 719, P/N (unreadable, believed to be 15750719)
I'm not sure why my torsion bars have 2 different colors on them. The keys are rusted so I have no idea what they were. I have been poking around FullSizeChevy.com and was pointed to this webpage:
http://www.gmfullsize.com/tech/torsion401.html
It was helpful and not helpful at the same time. None of the numbers on my bars appear on that list of GM pickup torsion bars. I take this to mean that the AWD vans have bars that are specific to them. The thought is that installing a torsion bar with a higher rating will lift the front easier but may make the ride harsher. Adjusting the torsion keys on mine yielded zero lift. I'm considering 2 different reasons:
A. The torsion bars could be tired at 120,000 miles and won't lift the van.
B. According to Photog (member here), GM independent front suspensions have limited travel so the shocks may already be sitting at maximum travel. Turning up the torsions bars won't yield any lift because the susp. has no where to go.
To test B, I need to unbolt the top of the shock and see if the suspension travels down further than what the shock allows. If it does, keeping the current bars and installing longer or adjustable shocks may be the answer. I haven't had time to do this.
Dwalt, another member here, has an AWD 1500 van with blue-coded torsion bars and was able to get some lift with doing nothing more than turning the adjustment screws. He has a newer model and uncertain why his bars work and others do not. I'd be interested to know what codes are pressed into the ends of his bars.
Nely - would you be able to look up those codes/part numbers I listed above and see if there is any mention of what their load rating is? At least that may give us some starting point for the 1/2 vans. I've been looking and can't find anything.
Thanks!