I have a 01 Ranger 4.0 and recently had the valve cover gaskets done because of a leak. when they were in there working on them they noticed that the rear timing chain alignment guide ( the cassette ) in they're words was "chipped on the top of the cassette." that goes around the tensioner. no Rattle of death or anything, and no noise coming from it at all. the shop wants a little over 4K for the work to do it. it only has 105k on it and I've read that its not uncommon for the Rattle of death to take something around that or under that even. What I'm wondering is if its something I should even be stressing out over. I haven't been able to find a thread on this kind of thing yet, if someone knows of one plz link it.
thx - sarah

 

Welcome to the Herd, as this appears to be your first post!
Lots of friendly knowledgable folk in these forums.

Have here same version of V6~4.0L~SOHC Engine+Fittings in a 2001 SportTracJob2 as in your 2001 Ranger.
In your pic, small chip in plastic upper corner of RearRight TimingGuide does NOT look too bad\catastrophic (may have been there since new),
but how loose was TimingChain? ValveCover leak may be from loose TimingChain slapping Cover; does Cover have cracks\scars from Chain?
If the Cover does have scars\cracks, yes you definitely need to renew this rear TimingGuide+Chain+Tensioner (pulling Engine, not easy\cheap).
If the Cover is NOT damaged & considering you don't yet have the "death rattle", as a MINIMUM I'd
* drain Oil & remove OilPan to inspect for schrapnel\pieces from broken TimingGuides & clean OilPumpScreen (relatively easy+cheap),
* renew both RightRear+LeftFront OilPressurized TimingTensioners (relatively easy+cheap, every 75kMiles\10yrs),
* fresh Oil+Filter (every 5kMiles\6Mths, easy+cheap insurance considering these TimingTensioners tend to sludge up & fail),
then hope TimingGuides hold together.

Click here for more info & various links on TimngComponents & related failures for the V6~4.0L~SOHC.
Hope this helps.