Hi,
Read the KDZ24 datasheet, that way you can compare similar parts. I think most important general parameters are Zener voltage, max surge current, wattage. KDZ24 is a 24V Zener,
the main specs are here.
Hopefully you know the circuit enough to have an idea of the current and therefore max wattage the Zener will see. Here's, for example, the
RS-Online 24V Zener list, you can see the datasheets for each part.
re the
U1JC44, the Toshiba rectifier, an equivalent part should be either of these two:
1N4005, Vishay or Diodes Inc 600V, 1A.