The conversion number is the FR8DPP30X. In Bosch's legacy numbering system the "PP" means double platinum, but the 6702 is single platinum. Bosch has created the confusion by changing the numbering scheme, but in any event that's a single platinum plug. (I'm guessing you found that number through an online reseller/vendor, and those conversion catalogs are not the most reliable.)

By using the single platinum plug you're reducing the interval to somewhere between 30,000 and 50,000 miles. The other issue is that the side electrode is going to wear faster, so your gap will deteriorate faster, and your mileage and performance will fall off as that happens. When it will first be noticeable is a good question, and due to the ECU compensating as it happens, you might drive several thousand miles before you catch it. In the meanwhile you'll have been suffering a loss of performance and mileage, which by the time you then change them may actually cost you more than using the correct plugs to start with.

Given that the only reason I can fathom to use the unspecified plug is to save a few bucks (roughly $50 on the V8 engine) -- and that you're already saving hundreds on the labor by DIY, my personal opinion is that sticking the 6702 plug in there is being penny-wise and pound-foolish.

That one of the best things about owning a vehicle is getting to decide the best way to maintain it, and my goal here is to get your eyes all the way open so you can make an informed decision, not to browbeat you into conformity.

Good luck with it. Assuming you're keeping the truck, please keep a close watch on the mileage and update us as you roll up some miles. If it turns out they are a solid deal all the way to 50K, then for many people that might be a good alternative.