1999 4Runner Limited - Stereo installation

I'm installing an after market stereo in a 1999 4Runner - Limited. The factory amp went out and i figured this is an opportunity to upgrade the stereo. i have the stereo, wiring harness, and installation kit. the only problem i have is that there are two connections in the factory stereo that look like antenna connections. I know one is for the antenna, but i can't figure out what the other one is. the car has a power antenna that comes on when the stereo switches to radio. i'm not sure if this is the power for that or not. there is also an antenna relay behind the stereo next to the factory amp. i figured this powered the antenna but now i'm not sure. does anyone know what this second connection is for? do i need some type of conversion cable for it?

any help would be appreciated.

thanks!

There are two antennas in your vehicle. The second one is in the rear side window. Get a splitter. If a splitter doesn't work for some reason, you will have to do without one or the other. The window antenna is called the "Diversity" antenna.