When looking at the TG-3541CE series of crystal oscillators from Epson, their part numbers will break down into 4 sections as shown below.
Applicable part numbers
TG-3541CE 32.7680KXA3 TG-3541CE 32.7680KXB3
SER4421CT-ND SER4421DKR-ND SER4421TR-ND
SER4422CT-ND SER4422DKR-ND SER4422TR-ND