You could simply test it !
Plug one in a proto-board along with a series 4k7 resistor on a variable power supply (or use a 4k7 resistor in series with a 10k pot on a 12 volt supply. Install a DMM on the proto-board across the DUT.
These shunts normally have a reverse polarity diode. So, when you'll try your shunt regulator,. you'll either see 0.7V,. 3.0 V or something like 11.9 volts. Try your TO-92's until you have the correct (3.0 V) voltage.
You can then use either the variable supply or the pot to check the shunt regulator under different currents. Most of these shunt references will work even with a very small current, so you'll be able to check the E/I behavior. If no configuration gives you 3,0 volts, try shorting two pins togethrt (either on the POS or the NEG side).