Those late model Magnum timing chain tensioners......

They were OEM on 3.9L V6's because over time the timing chain would develope slack and start slapping against the timing cover causing a tapping noise that sounds like constant lifter tap.

They are good, because they keep the slack out of the chain.....= more steady timing., and more dependable performance.

The OEM 318 Nylon Timing Gear was the WORST thing Chrysler ever did.....it caused more 318 A-body owners to scrap their car than, Rising Fuel Costs, Insurance Premiums, normal wear and tear, or the Highly Expensive and dramatic front suspension rebuild.

I have over 150,000 miles on a 318 with a double roller timing chain and THAT MP tensioner.......
I put them on every SBM " I " build.