Need replacement for these chanel balances

Thanks for posting. If the stamp reads 2020, then this is most likely either a S351-21 or S390-21 Channel Balances. The only difference between these two balance Series is the depth of the bottom nylon shoe, or the 'heel-to-toe' measurement. See the diagram below for reference. Compare both with your old hardware to see what matches best. In either case for a stamp option choose 2020.