If you don't mind having a white knob on your CT-100 this should fit. :D

http://cgi.ebay.com/1950S-RCA-VICTOR-UHF-VHF-TUNER-NEW-IN-BOX_W0QQitemZ6280817338QQcategoryZ3638QQrdZ1QQcmdZ ViewItem

For anyone interested in this unit, you may wish to ask the seller. These DX-3 tuners were shipped with a mahogany, beige and white knob set for teh tuner, as well as the papaer decals for the channel numbers.