The Crosley model 666 is a six tube, two band, A.C. powered superheterodyne. The 666 and 5666 are companion models employing the same circuit. The 666 employs chassis number 629, while the 5666, a console, employs the 644 chassis; the only difference was that the 629 chassis has the speaker mounted directly to the chassis, while the 644 has a speaker mounted to the cabinet.

The dual model numbers are confusing, until you understand that most Crosley radios from this era had both a sales model number and a chassis model number. Top this off with many radios also having a sales model name, and ...