I picked up this scope at an auction for very cheap, and I just want some opinions on whether or not it's original. The date and manufacturers mark are upside down if the scope is mounted, but the serial number is not. The center tube appears to be a slight plum color. There are some spots of what looks like old pitting. I have had differing opinions on it's originality, so I figure this would be a good place to ask. Please let me know your thoughts. Thanks!