AN LTT; ALONG WITH 2 OTHER NON-RPTING ACR ACFT; FOUND THEMSELVES ON THE GS BUT LOW OVER THE GND AT A DME FIX TO RWY 17L AT DFW.

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WE WERE TOLD TO CROSS PENNY INTXN AT 4000 FT. SLOWED TO 170 KTS AND CLRED FOR THE ILS 17L APCH TO DFW. WE WERE THEN HANDED OVER TO THE TWR. INSIDE PENNY INTXN; WE INTERCEPTED THE GS. ALL INDICATIONS NORMAL; NO FLAGS; IDENT OK; FO FLYING COMMAND BARS ON EFIS SYS. WE WERE ABOUT 4 MI BEHIND AN ACR B; AN LGT; ON THE APCH; EXPERIENCING SOME LIGHT TURB. JUST PRIOR TO JIFFY OM; WE WERE STILL ON GS WHEN I GLANCED AT THE DME AND SAW WE WERE LOWER THAN WE SHOULD BE FOR THAT DISTANCE FROM THE ARPT. WE STOPPED OUR DSCNT AT 1500 MSL. TWR THEN CAME ON AND ADVISED US WE WERE 1500 MSL AND ASKED IF THERE WAS A PROB. WE STATED THAT WE HAD A BAD INDICATION ON THE GS AND WOULD GO TO LOC MINS. THE ACR B FLT AHEAD OF US ON THE APCH THEN STATED THAT THEY ALSO HAD A PROB WITH THE GS. ACR A FLT Y BEHIND US STATED THE SAME THING. THE CEILING WAS 900 FT RAGGED AND WE SAW THE ARPT FROM 7 MI OUT. WE LANDED WITH NO FURTHER PROB. FATIGUE WAS THE MAJOR FACTOR IN NOT NOTICING THE ALT DISCREPANCY SOONER. WE SUSPECT THE GS INTERFERENCE MAY HAVE BEEN FROM CONSTRUCTION ACTIVITY NEAR THE RWY OR AN ACFT XING THE RWY.