A tandem wheel assembly or kit has a housing that includes a central chain box, a first wheel end casing, and a second wheel end casing. The central chain box has an internal volume extending between a first box end and a second box end, a unitary pivot portion having a box opening disposed about a pivot axis, a first box flange with a first box flange face and a second box flange with a second box flange face. The first wheel end casing has a first wheel end flange with a first wheel end flange face mateable with the first box flange face, a first wheel end opening, and defines a first length. The second wheel end casing has a second wheel end flange with a second wheel end flange face mateable with the second box flange face, a second wheel end opening, and defines a second length.