If you refer to photos of Erie's steam era fast freight trains (Locomotive Quarterly had some nice ones from Bob Collins) you will a lot of variation in the color of PFE reefers. Some are dark and some are very light.
I have found color photos of PFE ice reefers where the basic color has faded to yellow but the freshly painted repack area is definately daylight orange.
I recall Tony's book saying that some years PFE washed their reefers at least several times a year. Perhaps chemicals used in washing helped lighten the orange to yellow (Champ said PFE reefers were painted yellow; at one time I thought this meant school bus yellow {yellow with a little bit of orange}).
The dark reefers are easy to explain. Erie had a tunnel (Otisville tunnel?) not too far from the eastern end and under certain conditions trains would receive a heavy coating of soot.
Tony has a color photo of wood side PFE reefers on float in New York harbor and they all look to be similar dusty daylight orange.
I wonder about the color of MDT reefers in the '40s. Roger's book says orange but there are some Jack Delano photos of MDT wood reefers assigned to IC taken during WWII where the side color is definitely lemon yellow (no red at all).
