The proper name for the Dreadnoughts of the Greymanes is the Y-Gwasu o Blaidd-Tywysog (a phrase derived from the language families of the southerly Deep Valley). This phrase is rarely used around outsiders, for fear of its mythological and legendary references being inexplicable. The closest Low Gothic translation, however, denotes the high esteem the Greymanes hold their Dreadnoughts in. Indeed, it roughly means 'the retainers of the Wolf Prince', which speaks to the belief of the deified Russ ruling over sections of the conquered Underverse at Alwalda's behest. 
 

As a Ultima Founding chapter, they were given a number of Redemptor Dreadnought sarcophagi in their initial allotment of material from the Mechanicus. Many of these holy machines were the life-long works of skilled Magos artisans on the Forge World of Heliade and its oath-sworn Forge-moons. Over time, these initial machines have housed a number of the anguished, yet still courageous fallen. Names such as Asger Ironfoot, Camber Swiftwing, and Branulf Voidwolf (not to be confused with Branulf Bugslayer) are all redolent of the Chapter's history to the Greymanes. Though they have all willingly taken on the mantle of eventual sacrifice demanded of truly great warriors, each of the Y-Gwasu o Blaidd-Tywysog have passed into legend.

(Author's note: I also have a Redemptor, but I can't be bothered to photograph him right now for a fluff article.)