Yes, they should be horizontal so they aren't standing on the 'corner' of the lumber.Do you mean that the "rungs" are on the same angle as the "ladder" part?
It's a 1979 F150. Saw it at a car show. I have a 1995 F150.
Put the wide side up.
How long are the rungs?
Span might be too much for 1x when it's full of full sized birds.
Nice truck. Had a much older F100 years ago, loved that truck.