Anyone have info on the exit blocks on the mast? Existing single in line (2 sheaves in line, NOT double) Labelled "Fico FG943" I have been unable to locate any that fit without modification. I think the upper is for the spinnaker, and the lower for the topping lift, but I am not sure. None are available from Catalina, Catalina Direct, Rig Rite, Harken, Ronstan that easily fit. Thanks. Charles