Westend, I own this trailer, it's actually sitting in my driveway as we speak. I believe the door to be original as the wood panelling on the inside lower part of the door matches color and grain with the rest of the interior perfectly. Looks to me as if the siding is all original as the patina is exactly the same all around and the same screws are used in all places.
JJBIRISH, I thought that as well. However according to the Holiday Rambler club it's not one of theirs as all of them used the full Holiday Ramber name badge, while this one just says "Holiday" in a kind of balloon script over the windows.
Going to get in touch with the RV museum and see if they have any info. Thanks for all the input folks...