The male connector for an antenna is referred to as a 'motorola plug' and is available locally just about anywhere. Start with Radio Shack. Just solder on the new connector or clean up the old one, prep a fresh section of the coaxial and solder back on the old one. The AM/FM antennas are standard so any universal unit should do. It won't cost much more to go with an electronic/amplified antenna that will significantly increase your reception. There not very effective in automobiles because of the increase in multipath but they work perfect in boats.

David
Earmark Marine