I broke a spark plug removing it and found another that looks cracked - can I just replace the 2 in question or do I need to replace all the plugs?

Didn't find much on a search - maybe I wasn't looking with the right phrases.

Thanks

 

Typically when I change plugs and things like tires and hoses, I replace them all. That way you have the same wear, mileage and time on them. I also went with the Champion Truck plugs for my Ram as they are supposed to be more durable. Also, if you have enough mileage or age itself on it, you may want to change the cap, rotor and plug wires at the same time (Napa sells quality replacements). Mileage is not the only villian to wear on components, time is also.

Thats just my take.