I just bought an 80s Squier Precision to go with my MIM RI60s Jazz and am impressed with how much chunkier the P sounds (I've been playing bass for about two months now so these kinds of things are still new to me). I had been thinking the P sound must be the result of its pickup placement -- i.e. that it was picking up an especially fat sounding set of overtones that could only be picked up at that spot. But then I pulled out the measuring tape, and lo and behold both the P and J neck pickups are located at the exact same spot -- both have their polepieces sitting 11 inches below the 12th fret (measuring the E/A side of the P pickup). This means they're both reading the string in the exact same way. So it must come down to the pickup. The P pickup is just bigger and fatter sounding. Does this sound right to you guys? And of course the interesting conclusion is you ought to be able to make a J sound just like a P (or at least darn close) with the right neck pickup.