Got my replacement AM thumbwheel radio installed today!

Improve the sound of an AM radio? Yeah, right. Maybe the tone will change a tad due to the smaller cone diameter.

Be carefull how you wire two speakers to a single channel radio. If they are 4ohm speakers, as most common replacements are, then you should wire them in series. This means the wire out of the radio goes to the + terminal of speaker A. The - terminal of speaker A goes to the + terminal of speaker B. And finally, the - terminal of speaker B goes to chassis ground. This ADDS the the two speakers impedence so that the radio sees 8ohms. If you wire them in parallel, then the impedence would be 2ohms and you could burn up the output transister of the radio.

As for 'trimming' a radio, this is matching the the tuner impedence to the antannea. I picked op a Music Master AM for my Dart a few months ago. I haven't installed it yet because I have to fix the hole in the dash. Anyway, I can see it has some holes in the back whare you can access some trim pots. I don't know the exact procedure for these radios, but I assume you would try tuning in a local station as best you can with the tuner knob. Then try 'tweaking' the trim pots a little at a time to see if the signal strength gets better. If you attempt this, make sure you keep track of the original position so you can return to it. You don't want to make it worse than what you started with.