Hi,
this can be done by a simple unit, that can be buy from any electronics shop for around 400/=. it is a small 2"x1"x4" device run with 12V power supply. The antena cable should be directly connected to the this device, & the device have alternate antena cable should be plug to the radio. using this device connected to your old radio, U will be able to receive local FM cnannels. but the radio displays the frequency as FM76-FM90, but receive FM87 to FM108