Looks like about 23 inches. the drivers side it's the spare tire, the pass side its the fuel tank.
Seems like it would be much more difficult to lift a 6x6 and keep the articulation. The rear dogbones would have to be extended.
Like i was discussing with another member earlier. It all comes down to what the customer wants. If the customer would want air bags i would design a new drop down with a four link setup with DOM and heims as the link bars.
But if they want to keep the leafs this def posses a different problem. If we use a 5 ton back half you will gain 1.5" of lift to start off with. But the leafs are much wider which means that the leafs plates have to be redesigned to fit around the 2.5ton axles. Building a lift would consiste of a raiser block similare to my lift kit but much larger allowing the 5 ton drop down to bolt to it.
If keeping the 2.5ton setup is preferred i could redesign the drop down making it 8" taller and make new dog bones with DOM tube and 1" x 1.25 heims joints in single or double shear. Just some ideas i have been running threw.
so by your numbers it looks like the whole rear axle assemly would have to be lengthened cause i don't like the idea of the bars/ dog bones being different lengths, i would want to keep them all the same.
Kyle