In a routine injustice of cosmic proportions, WRIC Channel 8 shows reruns of old episodes of "Soul Train" at an unspeakable hour on Saturday nights. But if you can keep your eyes open that long, you might discover what's missing from today's music. Back in the day, "Soul Train" guest stars usually did more than just sing their song -- they performed. There was choreography, showmanship and professionalism. So much so that you'd almost forget they were lip-syncing. That's the kind of show you can expect at the 70's Soul Jam at the Landmark Theater Jan. 20 at 8 p.m. With classic hit-makers such as The Stylistics ("You Make Me Feel Brand New"), Bloodstone ("Natural High"), Emotions ("Best of My Love") and Heatwave ("Always and Forever"), you can bet your last money ($37.50-$42.50), it'll all be a stone gas, honey. 646-4213.