I'm not sure on that actually. That info is from 2001 series 1 paperwork that came in the leather folder thing with my car.
I doubt there would be a difference between H or A 3.8L V6, maybe it was purely a numbering sequence thing from the factory.
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I also play with Chryslers myself, and that manufacturer used 1 = low compression, 2 = standard performance, 3 = High Performance, 4 = Premium Performance (RT, Pacer, etc)
If you were unlucky enough to find a maltese cross on your Hemi engine number, it meant the factory stuffed up the machining and one of your mains was oversize, or a lifter bore was machined wrong, or cam journal was oversize, etc. Can't quite remember, but thats an example of a manufacturer coding a "We made a mistake, engine builder beware"
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So it could signify some small production difference like that. But its not compression as the S or R supercharged V6 code rules that out. All Supercharged L67 V6's had the same low compression and different pistons to the NA V6's. It may be something else minor.