1838 4-D is associated with the very large Clinton Head family. Most varieties in this family were struck on billon planchets, while about a quarter were struck on German silver planchets, such as this one. This variety is very rare with just 4 documented examples, which is roughly the median rarity for this family. This is the only documented variety struck on a planchet with the lettered edge die marriage LE.109-AAK (the publication on lettered edge die marriages is forthcoming)!
 
This example exhibits AG details and has relatively decent planchet surfaces.