Hi Jack,

I happen to have the manual for the radio (probably one of the few people who has a second hand car and has the radio manual left in the glove compartment) so you are in luck (even went out to the car to get it and look up your answer:)). to change the clock mode you will need to pull the radio out of the dash (not a hard thing to do, it pulls out fairly easily, haven't done it in a while but as I recal some gentle prying at the top of the radio will allow the radio to come right out). there is a switch on the back of the radio,

in the on position the time is normally displayed, the frequency can be called up for about 5 sec, in the off position frequency is normally displayed, time can be called up for about 5 sec. sounds like yours in in the off position, so go ahead and switch it. This should help (though if it like mine your am radio recetion will still be awful)