The FT100D is an updated version of the original FT100 that includes the following changes: It has a larger built-in speaker,a high stability crystal oscillator,a 500 Hz CW filter,and a CTCSS decoder. All of these features except the speaker were previously available as field-updateable accessories to the FT100.
Even though their cool radios and sometimes get crazy prices on Ebay....
I consider them ticking time bombs and will not pay over 3 bills for one.