According to the site at http://n9ewo.angelfire.com/kguvd1p.html there are 8 different versions. Judging from what I’ve seen on ebay, this would seem to be the case. All have the same lower range of frequencies but there are 3 different 220 ranges and 5 different ranges between 350 to 520 Mhz. It looks like differences in the RF deck of the second range of frequencies as the all have roughly the same bandwidth, just different upper and lower frequencies. I doubt that there is any firmware unlock that will give you all the range.