In the following link see item numbers 39. Thing is there are 3 different plug numbers. It would be in your best interest to both pull a plug and read some of the engine specifications stickers normally found on the engine to compare numbers to find the right plugs.....Sometimes depending on area you live/water you boat on, the law regulations may require a different spark plug thus the possible reason for the different spark plugs ranges/numbers. Hope this helps some, good luck.
| MERCURY | 2005 | 50 | 1050412DD | 40/50 (3 CYLINDER) 2-STROKE |
