This Accupsark Plug has the larger 18mm Thread and has the correct washer seal for the engine. 

This plug replaces 

Champion D16

NGK AB6

TRIPLE GROUND :
Upgrade your vehicle's performance with AccuSpark Triple Ground Spark Plugs, these plugs feature a triple-ground electrode design that offers multiple pathways for the spark, enhancing ignition reliability and reducing the chances of misfires. The durable construction ensures longevity, making them a cost-effective choice for classic cars like MGB, classic Ford, Mini, Reliant, and Land Rover. Experience smoother starts and improved engine performance with AccuSpark's proven technology.