Look these up?

14mm X 5/8" NGK BPMR6F or Champion RDJ6 or 7J but seems like they are all tapered. I'd have to go out in the garage and look?

My experience has been that I can interchange the tapered seat and gasket seat plugs on the same head or swap back and forth any time. This has been on McCulloch, Ryobi, and Homelite heads.

The "F" at the end on a NGK means tapered seat

The "DJ" on the champion means 14mm thread 5/8 hex and a .325 reach, tapered seat

<cite>www.ngksparkplugs.com/techinfo/spark_plugs/partnumberkey.pdf</cite>


http://www.spark-plugs.co.uk/pages/t...l/champjpg.htm