Sure is! I'll jump in before addo, and tell you its a VH 25 remote brake booster, like my old 1960 Vauxhall Cresta ran. If its faulty, it will allow your engine to smoke wickedly. It boosts the line pressure, and makes wheel cylinders push harder on the brake drum or disk.
The early Chrysler Hunters, Plymouth Crickets, Hillman Hunters, Sunbeam Alpines and the so-called Rootes machines Chrylser imported to America, Oz, and New Zealand ran them due to space limitations. Get it checked out. If its PBR or VH, there was a comprehensive rebuild kit around, but its ages old now. Ford used them on early Flacons in Oz, up till the XW when it got replaced by PBR bits.