Assuming that FedEx flies the same planes OUT as it flies IN, I checked the following link to get inbound FedEx flights to DFW:
ATL-DFW: Federal Express 79: Boeing MD-11
MEM-DFW: Federal Express 3488: Boeing 727 Stage 3 (-100 or -200)
MEM-DFW: Federal Express 3433: Boeing MD-11
Outbounds from DFW: FedEx 79 was headed to ANC, then "RJAA" (one of the Tokyo, Japan airports.) The other two appear to be either overnighting or returning to MEM.