RadioBanter - Speakers for pick-up truck

I recently bought a used Mazda B2500 pick-up truck.

The factory sound system had a quadraphonic sound system option.
Apparently the truck only had a stereo sound system installed, no speakers
were ever installed in the two speaker ports on the rear wall of the cab.

The two speaker ports near the floor on the rear wall of the cab will hold
5"x8" or 6"x9" oval speakers.

I am going to install a Dual Band, Dual Receive 2m/440 transceiver (Icom
tm-v71A or Anytone AT5888UV).

I would like to put speakers in the empty speaker ports, and dedicate the
one speaker to left audio channel, and one to the right audio channel.

I have looked for speakers that will fit these speaker ports; but all I find
are "high performance" audiophile music speakers that have audio responses
like "50Hz to 44000Hz".
This is way overkill for my application.

What I need are speakers that are tailored to Voice frequencies; say 300Hz
to 5000Hz, that will fit into the speaker ports.

A strong roll-off below 300HZ will help suppress hum from CTCSS.

Does anyone have an idea where I can purchase speakers with these specs?

I am looking for Recommendations of specific makes, models and vendor URLs.

Dan
AI8O at YEMIOLA dot NET