Anyone know what it's worth? Been thinking of selling it as I won't be using it, it's been laying in the loft now for for at least 65 yrs without me needing it for anything
I know very little about selling this kind of vintage equipment since, when it comes to tools, I focus strictly on hand tools and vises. But I do sell other vintage items too, and so I can give a semi-qualified opinion.
Little Giant went out of business in 1982 from what I found online. Couldn't find a modern rough equivalent online, so it doesn't look like they make winches configured like this anymore. it looks older to me than 65 years. Doesn't matter if it isn't, what matters is that it has that look. This makes it game for either a user or for interior/exterior design--industrial salvage is big today. Someone has a restored rustic barn or outbuilding might paint that up and display it. Might even be re-purposed for a table base. For this, you need to find the right buyer, which is difficult in that market.
I could find few comparables on eBay. Small ones sold for $80-100. Someone had a similar one to yours who was asking $500 + local pick-up only and took best offer--eBay doesn't show what the best offer final sales price was. In any event, I think finding a buyer for this particular item will be difficult for any kind of money unless you want to sell it off cheap. At 100 lbs, you'll probably have to factor in building a crate for it if you want to ship it.
A local antique dealer who has a clientele of interior designers would make a quick sale, but you won't get much.
A user might buy it for nostalgia purposes, but power winches have taken over this category, and this probably offers little advantage other than the coolness of having and using it (unlike, say, an antique hand wood plane which are prized for their exceptional quality when compared to most modern offerings).
All in all, I think top dollar will be in the $200-$300 price range. That's my assessment based on being familiar with collectibles but barely familiar with this kind of item.