Ask each of the spring providers what the weight rating of their springs is, or what the pound/inch resistance rating is, and you will know what they are expected to bear in extra weight, assuming you also know what the stock springs are rated at. There are a number of places on the net where you can find correct formulae for determining the rate needs of your springs based on the load you intend to carry. Lift, on the other hand, has nothing to do with load rating unless you have accomplished lift by use of overloads or AAL style leaves. A properly designed spring, leaf or coil, will both bear the load you need and provide the lift you want. Rather than shopping by brand and hoping that what you get is what you want, shop by spring parameters, availability, warranty or reputation, and price. I would expect Alcan or Deaver to be able to build what you need. I would expect OME to simply sell you what fits your truck. Not the same thing.
