Heads shear off the manifold bolts - very common on 4.7 & 5.7 and yes it's possible after time the manifolds can warp. Although if a couple bolts sheared you'd still get the lean code from exhaust escaping - that alone doesn't mean they are warped.

Yeah, they are raping you on the repair. Hell, I purchased stainless headers, had them custom ceramic coated and didn't have $700 in them.

I'm not sure how tough it would be to remove and install yourself on a Durango. My Ram had 4" of lift and by just removing the wheel well liners I could get to everything without lifting or even removing the tires.

I had a 4.7 HO in a Grand Cherokee broke the back two studs on the passenger side. It wasn't too bad to get too, although I lot harder than the 5.7 on my Ram. No warpage and it just took a $20 set of Grabits broken bolt extractors to get the bolts out.

Word of advice if you do it yourself. Don't use grade 8 bolts. Although stronger they will snap rather than give. Use grade 5 bolts...

 

I agree with Hammer. You can get a set of headers for about $1,300.00 or much less depending on the brand and coatings. I have a set of Stainless Works exhaust headers on my 2014 Jeep SRT and they were about $1,400.00 and that included two high flow catalytic converters.

 

Hell, a two minute search and I find shorty headers for '04-'08 5.7 Durango starting around $350 and ceramic coated, CARB approved for $700.

If its determined the manifolds are bad, get you some headers. I've always firmly believed a repair should be a mod, especially when the mod is cheaper than going back to poorer performing stock...

 

I had a set of JBA shorty headers on my 2007 5.7 liter Hemi Durango. I do not remember the price, but I would guess around $500.00.

 

I had a repair on the exhaust manifold done, with a new loud muffler for $700. My O2 sensors weren't involved though.

 

These manifold bolts came off on one of our 2nd gen trucks, I changed the bolts and gaskets myself, right in the truck through the inner fenderwell. Code gone, exhaust leak gone, spent less than 30 bucks. They're overcharging.