Jim, back when I retired from running Skycraft Electronics nine years ago, both these transponders were considered bad news. Both types used earlier, inferior technology with many individual adjustments which became very unstable with advancing age. I understand that not everyone can afford to buy new avionics but a good second hand KT-76A with it's microprocessor controlled technology would be a much better proposition if one can be located. IMHO, any money spent on the models you mention may not be money well spent. John.