Lock assembly with interchangeable key plug

A lock assembly comprising:

• key plug having an axis;
• a first housing defining a receptacle for the key plug;
• said first housing guiding movement of the key plug in the receptacle around the key plug axis;
• a latch assembly including a first movable latch element;
• means cooperating between the latch assembly and at least one of the key plug and the first housing for supporting the latch assembly in an operative position wherein the first latch element is movable between the first and second positions relative to the first housing;
• a retaining element;
• means mounting the retaining element to the key plug for movement relative to the key plug between first and second positions,
• said key plug being selectively movable into the key plug receptacle to an operative position and removable from the key plug receptacle with the retaining element in its first position;
• and
• second means cooperating between the retaining element and the first housing for preventing the key plug from being moved axially outs of its operative position and fully separated from the first housing without rotation of the key plug relative to the first housing with the retaining element in its first position,
• the second means comprising a surface extending at least partially around the key plug axis, the surface disposed at an angle less than 90.degree. relative to the key plug axis, the surface and the retaining element being abuttable to each other to prevent the key plug from being moved axially out of its operative position and fully separated from the first housing without rotation of the key plug relative to the first housing with the retaining element in its first position.