Obsolete — sourcing through independent channels
Diodes Incorporated lists the 1.5KE56A-T as obsolete.
1500W clamping — what the ratings mean for the circuit
The reverse standoff voltage of 47.8 V means the diode stays out of the circuit below that rail voltage — it only conducts when a surge pushes the line above the breakdown threshold of 53.2 V min. This is a unidirectional Zener TVS, so it clamps positive transients only; a bidirectional device would be needed for AC lines or reverse-polarity protection.
DO-201 axial — field-serviceable through-hole package
The DO-201AA (DO-27) axial-lead package is through-hole mount — no hot-air station needed, just a soldering iron and a steady hand. The body is large enough to read the marking without a loupe, and the polarity band is clear.