I have a recording that has a lot of background noise, like loud muffler from a truck and the radio is on with both music and talking.. I need to clean it up to be able to hear only the people inside the vehicle talking...
You could try Magix SpectraLayers Pro or iZotope's RX. Typically, neither will remove all the extraneous noise, but may make the voices a little more understandable. Either way, a lot of money and time will likely be needed. If it's for a film, ADR is another option