I just discovered what appears to be the "freeband" mod for the US version of the VX-6R. It requires the removal of one solder blob.
Here's the procedure:
Turn off the radio and remove the battery.
Remove the stick-on plastic cover that fits over the cutout where the SU-1 goes.
You will see two rows of solder pads, one row of eight (with two pads soldered) and to its right, one row of five (with no pads soldered).
Counting from the left on the row of eight pads, go to the fourth pad and remove the solder from it.
Replace the SU-1 cover and replace the battery.
Reset the microprocessor.
The radio will now transmit from 137 - 174, 222 - 230, and 420 - 469. The TX LED lights up in many other ranges but I have not checked power output anywhere but in the ranges I just mentioned.