They're as "necessary" as windshield wipers on a duck's backside. The place we usually found them was at the bottom of an inch thick layer of sludge at the bottom of the oil pan. Save a little time and effort and toss them into the pan before you bolt it up, if you feel like they really need to be included in the rebuild. A properly torqued rod nut will not loosen up, whether or not it has a palnut added. One that's not torqued right won't stay together, even with the palnut added.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!