Legacy Motorola radios require a hardware Radio Interface Box (RLN4008) to manage data voltage levels. A standard cable connects your PC to the RIB, and the RIB connects to the radio.
So you found a classic Motorola GM350 but need the software to program your frequencies? Here is the quick download advice: Motorola Gm350 Programming Software Download
If the software opens in a foreign language (e.g., French or German), delete the rss.cfg file in the application folder to reset the language to English. Legacy Motorola radios require a hardware Radio Interface
Even with the correct setup, issues can arise. Here are some common problems and solutions: French or German)
The Ultimate Guide to Motorola GM350 Programming Software Download and Setup