SWITCH2D550 Regulator by the D550 Digital Regulator Kit All-in-one kit that allows you to quickly replace an analog regulator by the D550 digital regulator. An alternator equipped with an analog regulator R449 or another regulator associated with an optional R726, R729, R731 or R734 module, can use the SWITCH2D550 kit to upgrade to the D550 digital regulator.