WLDR is usually on top, but I've heard WDEZ Wausau, WI and WTMX Skokie, IL there as well. I've also heard both in Manistee, 20 miles closer to WLDR. This summer it's occasionally been a sloppy mess of WLDR and WDEZ (both are country stations).
Next: 107.9 MHz in Frankfort, MI (just did this yesterday)