Chrysler Repair: engine knocking: rocker arm service? 3.5L , chrysler service, rocker assembly

Question
I read a response about a temporary gap between the valve stem and the rocker arm.  Well, one of my problems is, at least one of the non-adjusting [lash adjuster plastic] retaining caps is broken and needs replacing.  It is the little piece on the rocker that effectively goes between the rocker and valve stem.  I figure I want to replace all 24 as they have over 170,000 miles.  Certainly they must be available somewhere without buying the rocker [assembly/ies].  Maybe a manufacturer?  If so, where?  I've found some exploded views of the area on the Internet, but none have separated that piece from the rocker.

2001 Chrysler 300M 3.5L  (I've used synthetic oil all the life of the car.)

Thank you in advance for any help.

Answer
Hi Jim,
As I read the Chrysler service manual about the 3.5L rocker arms I get the distinct inpression that these are so complex such that replacing individual parts is not likely to be a satisfactory solution to one sub-part being worn. That is probably why they don't sell the plastic retainer caps but instead recommend rocker arm replacement. You may get an answer from an engine rebuilding shop if there is one nearby that you can visit. But it seems a better idea to replace a known faulty rocker with a new one rather that to try and replace that specific part on all the other 23 rocker arms, prophylactically.
If you determine that there is such a part source and that it is likely to be a successful transplant project do let me know.
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Thanks,
Roland