The Boy Scout motto is "Be Prepared." Here is most of what you need to deal with broken spark plugs in your 3V Ford Modular. The cost of this would be around $250 in most places. Our informal survey of the costs of having it done at a dealer or independent repair shop range from $600 to $1,200, with only a few broken plugs. If parts fall into the cylinder and the head must be removed (which necessitates lifting the cab), the cost can run $2,000 to $3,000.