XM radio is via satellite with some repeaters. In the DFW area here is a list:
Dallas Ft Worth
Site Latitude Longitude BW Dir EIRP Height
DFW004A 32 59 03 N 96 42 50 W 90 20 4320 260
DFW005A 32 51 52 N 96 48 37 W 90 0 3076 220
DFW006C 32 54 40.1 N 96 52 34.6 W 90 330 3450 200
DFW011A 32 45 11 N 97 19 46 W 90 230 2014 520
DFW013B 33 14 23 N 97 07 57 W 120 0 2326 170
DFW019A 33 02 26 N 96 58 19 W 90 320 3932 300
DFW030E 32 36 17.6 N 97 11 12 W 90 220 2440 160
DFW507B 32 49 54 N 96 54 43 W 45 270 5132 270
DFW512D 32 44 28 N 96 53 42 W 90 225 4100 250
DFW515B 32 52 39.6 N 97 04 56.1 W 45 290 5540 175
DFW517B 32 48 35.7 N 97 06 05 W 45 270 5720 190
DFW518A 32 44 23.9 N 97 06 41.8 W 90 210 3988 300
(from the FCC filing).
There is no tower in east DFW. The closest is in Plano, TX.
Here are the towers on a map, in case you are not familiar with Longitude/Latitude.