Fat Man (Mk 3) Nagasaki Atomic Bomb:

Another Fat Man Atomic Bomb can be found at the US Air Force Museum in Dayton, OH	The Boeing B-29 Superfortress, BOCKSCAR, that dropped the second atomic bomb on Nagasaki can also be found at the US Air Force Museum in Dayton, OH

Length: 128 inches
Diameter: 60 inches
Weight: 10,300lbs
Weight of Fissionable Plutonium: 30lbs, 2.5lbs of which actually fissioned
Explosive Yield: 18-48 kilotons
Configuration: Plutonium implosion bomb
Delivery Method: Air dropped by Boeing B-29 Superfortress BOCKSCAR
Detonation Altitude: 1,800 ft
Est. # of Mk 3 Atomic Bombs Produced: 12
Target: Nagasaki, Japan (Kokura was the primary target but obscured by cloud cover)
Delivery Date: August 9, 1945 11:02am JSP

This is a bomb casing of the Mk 3 series Atom Bomb, the same size and configuration as the Fat Man Atomic Bomb.

Here is a link to a page showing wartimes photos of the Fat Man plutonium atomic bomb being prepared for loading into the B-29 BocksCar. What I found interesting was that a number of people actually signed their names and left comments on this top secret weapon.