5.0L and 5.8L crate engines and cylinder blocks are for the Windsor series of small block Ford engines. These engines appeared in Mustangs from 1965-1973 and again from 1979-1993. The only difference between the 5.0L and 5.8L engines is that that the 5.8L has a slightly larger displacement.
These crate engines and cylinder blocks are all performance replacements for custom builds. The crate engines are basically ready to go out of the box. They come preinstalled with the valve train, cylinder heads, intake manifold, and other components. If you buy a cylinder block, you'll need to get those items separately.
Ford Performance carries several crate engine and cylinder block options. Ford Performance crate engines are designed for increased strength compared to stock engines. They deliver large amounts of power while maintaining drivability. A new Boss 302, Boss 363, or a 427-cubic inch engine will last for years to come and make driving your Mustang more enjoyable.
Edelbrock offers a few small-block Ford 347 crate engines. They're engineered for performance and durability. Although crate engines are an investment, they'll provide unrivaled power gains.