I HAVE A 998 AND A 859 ON BACK,IS THERE ANYWAY U CAN BUY OR MAKE CONNECTOR THAT WILL LET BOTH UNITS USE ONE 2D FOR BOTH AND AT SAME TIME DI ON 859 AND SI ON 998 SO WOULD NOT GET INTERFERENCE OR MIGHT DAMAGE UNITS AND OTHER UNIT 2D BE SHUT OFF.I DON'T THINK SO ,JUST A THOUGHT