GK stands for junk. I have seen people try to get away with using them in the past and they outright fail. When I see one leaking on a car (the GK) I have to charge the customer for a core. Mercedes OE REMAN water pumps are soooo cheap now, I don't know why anyone would use anything else. GK is not OE quality.
1981 280GE SWB
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM