Ok. Wasn't sure. My theory posted above is purely. "tounge in cheek". I really would have no idea the difference in thrust plates. But, going back to your OG question, the majority of LA(early and late), and Magnum V8 that I have disassembled have had the plugs. I have no concrete evidence that it HAS to be one way or the other. I do have a SBE Magnum coming up, I might have to do some experimenting.