Yeah, like with a lot of these restoration suppliers, their website sucks. You've gotta call them for this type of item. They've got about 3-4 pages of u-nuts in their massive hard copy catalog. Sounds like you found what you needed though, so that's all that matters.
Yesterday was very frustrating. Your right about the websites. Typically when I call they are looking at their website as well and conversation goes stale quick. Hard to find anything close to these little buggers.