Further info. Apparently the NGK laser iridium plugs as well as having a thin iridium central electrode also have a tiny platinum disc attached to the ground electrode. This would leave the LTR6DI superior to the LTR6IX. This ties in with the double iridium Bosch plugs Chris and John recommended.
Using the latest type may offer greater availability and reduced price as demand for same as replacement increases rather than seeking a perfect match for OE, given engines were likely designed 10+ years ago.
If using NGK I would check the suffix though which defines the factory gap setting. Indeed it might be worth checking gap anyway.
![[Linked Image]](https://s3-us-west-2.amazonaws.com/monarch-public-assets-prd/images/thumbs/0191903_ngk-90495-ltr6bhx-ruthenium-hx-plug_550.jpeg)
To muddy the waters further NGK (and likely others) are now offering Ruthenium plugs as above with this rare earth central electrode working with platinum tipped ground electrode (as shown) to give better flame spread and twice the life of iridium type
