Anyway, I picked up a new Yaesu FT2D yesterday. I'm trying to get over 
the programming hump. In the box with the FT2D was a USB programming cable.

Win7:

Yeasu in-the-box supplied Prolific cable and driver from Yeasu's web 
site won't run. v1.8 driver fails to install. I downloaded and the 
latest v1.16 driver from Prolific's web site, still no love.

What makes you think this is a Prolific driver? Is it printed on the CD or something? I did look at Yaesu's website, their driver installation, etc. and I would agree.. it looks like a Prolific 2303 based cable. Now the question is.. is it a REAL prolific, a knock-off, maybe an RT System's cable, or it's fried?

Ubutnu 14.04 LTS:

Now it gets interesting. lsubb reports PID/VID for this cable:

    Bus 005 Device 016: ID 26aa:0001

The pl2303 kernel module doesn't recognize this PID/VID as a serial 
device. When the cable is inserted, the kernel doesn't load the serial 
USB module. "modinfo pl2303" doesn't list this Yeasu cable's PID/VID.

That's not a recognized Vendor ID for Linux:

http://www.linux-usb.org/usb.ids

Looking at my Yaesu cables via my LInux box (kernel is 4.8.4):

FT1D
--
usb 2-1.3.3: new full-speed USB device number 13 using ehci-pci
usb 2-1.3.3: New USB device found, idVendor=067b, idProduct=2303
usb 2-1.3.3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
usb 2-1.3.3: Product: USB-Serial Controller
usb 2-1.3.3: Manufacturer: Prolific Technology Inc.
pl2303 2-1.3.3:1.0: pl2303 converter detected
usb 2-1.3.3: pl2303 converter now attached to ttyUSB8
--

FTM400
--
usb 2-1.3.3: new full-speed USB device number 14 using ehci-pci
usb 2-1.3.3: New USB device found, idVendor=067b, idProduct=2303
usb 2-1.3.3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
usb 2-1.3.3: Product: USB-Serial Controller
usb 2-1.3.3: Manufacturer: Prolific Technology Inc.
pl2303 2-1.3.3:1.0: pl2303 converter detected
usb 2-1.3.3: pl2303 converter now attached to ttyUSB8
--

I borrowed a neighbor's FT2's cable and it's just that.. a plain USB cable. He says it's the right one.. but its not the SCU-19 cable as the manual shows. I can't try the radio itself as his radio is back at Yaesu for a battery drain issue (8 weeks and counting).

When inserting the USB-serial cable, while the FT2D is in "clone" mode, 
syslog reports:

The cable needs to be identified as a serial port (which your's isn't). As such, this won't work.

I tried manually to force load the kernel modules and force the PID/VID 
into the drivers -- but still nada:

   sudo modprobe pl2303 vendor=0x26aa product=0x0001
   sudo modprobe usbserial vendor=0x26aa product=0x0001

I don't think you need the second line above. From my notes at http://www.trinityos.com/HAM/CentosDigitalModes/hampacketizing-centos.html#2c.kernelnavigatorudev . Try this approach (assuming your cable really is a Prolific or Prolific emulated serial chip):

modprobe pl2303 vendor=0x26aa product=0x0001
/bin/echo "26aa 0001" > /sys/bus/usb-serial/drivers/pl2303/new_id

I looked over the CHIRP source code and with the kernel modules "forced" 
and the FT2D still in "clone' mode, then launched minicom on 
/dev/ttyUSB0. Set the baud rate to 38400 8N1 -- nada. Nothing to/from 
the FD2R.

Either the FT2D nor the FTM400 is supported by Chirp today - http://chirp.danplanet.com/projects/chirp/wiki/Wiki

This should be this hard (well, except for windows).

No.. It's usually quite simple unless you're using proprietary cables likt RT System cables. Fortunately, those are using FTDI based chips and the VID/PIDs can be re-programmed to look like a standard serial cable.

I checked over the last year of the CHIRP mailing list and didn't find 
any posts relative to the FT1D or FT2D, so I guess I'm breaking new ground.

The FT1 is supported and I've used it with my SCU-19 cable.

--David
KI6ZHD