CB World Informer Home
This one is similar to the Washington chassis but already has the 11.3258 MHz crystal in the circuit. The 5.6µh choke is needed for the extra range and a super diode in place of the stock varactor diode would give the best range.
The following instructions will open and increase the clarifier range:
There are other radios that use these chassis and the mods. would be the same. You'll just have to determine which chassis are the same by looking for commonalties for yourself.