The most common number is 1N4001 through 4007. Probably the 4007 is most available. Any diode will work fine so don't get too wrapped up in the search. The suppression current peak is the same as the load you are protecting and is a short pulse. The 4007 is plenty for loads up to 100 amps. The continuous rating for the diode is 1 amp which is also fine for the reverse battery protection diode in series with the master solenoid.

Good luck with the project.    Jack