Why is my truck not level?

[RShaips]

I am building a 72 1/2 ton 4x4 , I have a different cab thats been restored and set on the original frame, new 6" lift from Tuff Country, new springs, shackles and bushings all around. My truck is almost one inch higher on the passenger side in the front. I know I can shim my cab up some to help but it should not be this way. The frame is straight and measures the same from the ground on both sides. All I can think of is that the front springs don't match. Any suggestions on what else to check. The back is only about a 1/2" off. Thanks