D-326 looks like a big brother to what is now the Agusta A609 (formerly Bell-Agusta BA609). One of the more interesting ones is the D-300 which was an iteration toward what became the XV-15, it looks very much like a long MU-2, with the short MU-2 main gear, with the XV-15 wing (appropriately enough, the Aerophile article on the XV-15 shows that Boeing's entry was based on using a long MU-2 fuselage). It's a temptation to get the resources together to model that one.