ACR FOLLOWING MARSHALLER INSTRUCTIONS TO PARK AT GATE HAS WING TIP STRIKE DE-ICE TRUCK.

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UPON TAXI IN AFTER FLT SEGMENT (SBN-DAY) I MADE A L TURN INTO GATE AT DTW TO TAXI UP TO JETWAY. THE GND 'MARSHALLER' WITH ORANGE WANDS WAS ALREADY STANDING THERE TO WAVE ME IN. UPON TURNING ONTO THE YELLOW LINE; ALL MY ATTN WAS THEN DIRECTED TO THE MARSHALLER. ABOUT 20-30 FT FROM THE GATE THE ACFT LURCHED SUDDENLY WHERE UPON THE MARSHALLER THEN GAVE THE SIGNAL TO STOP. THE ACFT AT THAT POINT HAD ALREADY MADE CONTACT WITH A DE-ICING TRUCK PARKED AT NEXT GATE; DAMAGING THE L WING TIP. AFTER ACFT WAS DEPLANED AND DEBRIEFING TOOK PLACE ON THE GND; THE GND MARSHALLER DID VERBALLY ADMIT THAT HE HAD NOT PAID ATTN TO THE WING WALKERS ON SIDE OF ACFT TRYING TO TELL HIM TO DIRECT US TO STOP ACFT. AS PIC OF THIS FLT; I ONLY FOLLOWED HIS STANDARD HAND SIGNALS AS PER OUR AIRLINE SOP'S AS I TAXIED SLOWLY INTO THE GATE WITH ONLY 1 ENG RUNNING AT THE TIME OF OCCURRENCE. SUPPLEMENTAL INFO FROM ACN 203372: AFTER DEPLANING; THE WING WALKER RPTED TO ME THAT HE TRIED TO SIGNAL A STOP; BUT THE MARSHALLER DID NOT LOOK AND DID NOT SEE HIS SIGNAL.