It will sell quickly if you have all the attachment hardware to put it onto a tractor, but if it is just the blower itself, it is worth whatever someone that has the attachment hardware is willing to pay to have a spare one for parts. You say that you have never used it, but that doesn't say that it is new or used. I just looked up the parts on the unit and noticed that there are some expensive driveshafts that drive the unit. Without these, it might be more difficult to find someone looking to install it on a tractor that has never had one on it. If I had that tractor and snowblower, I would definitely buy it for a spare should I ever need an expensive part for the one that I was using.
A new never used snowblower has slightly more value, but you also have to keep in mind that it is approximately 23 years old and the tractors that it fits are not as prevalent as they once were. Of the last 2 snowblowers that I purchased, one was complete with all the mounting hardware purchased from a Kubota dealer as a used item was sold at approximately 50% of new, and the other that I bought used a couple of months ago I paid 45% of its new cost. Both of these units had 1 year of use on them.