Any shop or auto parts place should be able to tell you the type of plug you need just from make, model, and year.DPREA-9 sounds right. Any brand ie. champion, bosch etc will work, but you will find nothing will work as well or last as long as an NGK plug. I have tried them all in a host of different machines and nothing is as good as an NGK. I have even switched all my cars and trucks over.
standerd ngk r plug model number DPR8EA 9 is what I run and what are factory manule says. can be bought from any autoparts store that i know of. Comes pregap but always check. Are manuel says 0.8-0.9 or 0.031-0.035 torqe to 14lbs.