Looks like that particular company is out of business?
These should be the same from what I've seen. https://sealsit.com/product-category/axle-seals/
Personally, I like DANA/SPICER.
On cheap brands, I've had greasable and sealed units fail shortly. Ujoints and balljoints aren't something I like to mess with often, so I tend to at least start out at the upper price range parts.
Looks like Ospho is an old-school phosphoric acid product, so it requires a rinse afterward. With Coroseal, it cures as a hard primer, so you don't have to worry about your rust converter causing even more rust (or interfering with your primer system).
http://corroseal.com/rust/convert-rust.aspx
So far it's holding up better than a brand new receiver I bought for my Dad. In that case, the powdercoating is coming off in huge flakes:***:
EDIT: Okay, I might not be 100% on how Ospho works. Usually the phosphoric acid products I saw/used required a rinse afterward but this might be different.