[dsraven]

yeah, check to ensure the cab is parallel to the frame. i assume these parts were together on a truck at some point, not individually bought items from different trucks?
if the cab isn't square with the frame then you can still make the parts fit if they fit at one time on another truck, it just won't be in the middle of the frame at the front when you are done.
draw it out on paper and you will see how things can easily get outta whack if the cab isn't sitting on the frame parallel.