Why does my truck lean on one side?

[72gmcshorty]

I have rebuilt my frame completely. I didn't notice that it leans lower on the front drivers side. With the fenders on, the left is about 1" lower than the right side. I have new springs, shocks, spindles. I did replace one upper a-arm. Is there a difference between 1/2 ton and 3/4 ton upper A -arms? I'm not sure what size truck the one I got from the junkyard was off. I know it's the correct year though. I had a wheel alignment done without the motor in. The guy said to bring it back after it was done. Could that cause that much lean? I measured the same spot on the lower control arms and the drivers one is 1/4 lower than the other side. I have no clue as to what is wrong here. Possibly spring not installed properly? Any ideas?