27 4 FX CMC 7 and 27 4 FX CMC 11

Thanks for posting. It appears you have either the S380-28 or the S385-28 Channel Balance. The only difference between these two balances is the depth of the bottom nylon shoe, or the 'heel-to-toe' measurement, so compare both with your old hardware to see what matches best--see the diagram below as a reference. In either case, for a stamp option go with 2740.

Comparison of the S378, S380 and S385 balance shoes.

Those digits are manufacturer codes that frankly aren't that important. The only important numbers in the stamp are the first 3 or possibly for digits (for instance, 27-4, or 2740). These numbers are not identification codes. They simply denote the balance's strength. Channel balance identity is determined by the nylon attachments at both ends. Let us know if you have further questions.