Is there a way of playing my MP3 player or Ipod through a car radio that precedes the new ones with the appropriate connectors.

e.g. bluetooth

Yes.
Now if your radio doesn't have bluetooth or accesory connections then you need a iTrip; ( Amazon.co.uk: Griffin iTrip - FM Transmitter for iPod Video - Black: Electronics & Photo )

Basically this transmits your iPod on the FM wavelength so your radio can receive it.

Thanks CB

Is there one for an MP3 that connects through the audio skt?

MAC

I believe there is a more generic model available, but really depnds on personal taste.

Have a look at these: Amazon.co.uk: FM Transmitter - Electronics & Photo: Electronics & Photo