Jim-Bob,
The gray primered truck is a '57. That grille is a one year only as is the oval fender emblems. Also note the two raised detail lines on the hood - all '57 details. I don't know about now but years ago when I had one, '57's were highly desireable.
As for the copper one, you can't tell what year it is from the pictures because the body has been shaved of the emblems. See Wrenchbender's post #2, note how the hood emblem is long and runs along the crease in the hood/ Also note the fender emblems are above the body line. On a '55 the hood emblem is not as long and is above the crease. The fender emblems are below the body line. There may be other details that differentiate 55's from 56's but I'm not sure what they are.
Here's a picture of the fender emblem temporarily mounted on my '55:
Here's a picture of another guy's BEAUTIFUL '55 panel with the hood emblem showing:
Oh and before you ask, as far as I know that bird hood ornament on the panel never came on '55''57's. I THIN K you could get it on a '58-'59, but I'm not certain.