I forgot to answer this
Steve wrote:
I think you said I want the front end to raise 1/8" to 1/4" vs un hitched right for 150# lighter? Is that correct?
On my V10 gasser this 1/8" to 1/4 is approx 100 to 150# lighter. On your 6.0 diesel, that puppy weighs more and the front end has stiffer springs. On yours, 1/8" may be more the ~ 100 to 150 and 1/4" may be more ~ 200 to 250#
One of these days I may get a oil burner verses a gas guzzler and then I can report better on the spring pack changes. :)
Per the Ford truck manual for your vintage, you can if needed go to zero front end fender height change before and after. Even a litte lower. BUT the truck rear should never be above unhitched height when WD is engaged. Always want some squat back there. When Air bags come, this will even be all that much more important.
Your aux fuel tank is loading the truck more to start with. The spring dynamics are a little differnt.