DerbyDad03 wrote:

-snip-

I'd like one that's tied directly into the antenna lead (so it
would override any local station) but haven't found one yet.

Here's one for $27- free shipping
http://www.amazon.com/gp/product/B00...00_i00_details
Scosche FM-MOD02 Universal Audio Input FM Modulator

How would something plugged into the antenna lead override a local
station? Wouldn't the radio waves still see it as an antenna, albeit a
lousy one, and find their way into the receiver?

Yes. It is more discriminating than the transmitting FM
modulators-- but the one I posted the link to has 2 stations you can
switch between if a station interferes.

I'm in an area where the modulators are practically useless. I have
to switch stations every 1/2 mile & sometimes none of the 3 will work.
I haven't touched the Scosche one since I put it in.

One day I was in an area that started picking up a little
interference, but it never got bad enough to make me switch stations.

Jim