Duplex Digital Board ("phone plug" type connection for topside panel).

Replaces 1900DR1A, 1900DR1D, 2500ESR1C, 410ER1C, 51405, 51542, 51569, 51586, 54003, 6300DR1A, ALP50R1C, BH50D, C11JDR1A, C11JDR1B, C2000R1A, C2000R1B, C2000R1C, DAK50R1B, DIGDUPR1A, DS50R1A, DS50R1C, DYN100R!E, DYN100R1C, MAS125R1A, NOR124R1E, P295R1A, RET50R1A, SS23DR1B, SS23DR1C, VIK100R1A, VIK100R1B, ZX500DR1A, BAL54003, 611311, 9710-09.