It's not just Mopar V-8's. Chevy and Ford trucks have the issue as well. Funny you don't see it in 4 or 6 cylinders engines.
Doug

Oh OK if you say so I trust you.

But let me ask you how come it is almost entirely the end bolts that break? The center ones get just as much tensile stress but I have never seen one of them break and I have replaced 100s of them, the sideways movement is much greater at the ends than at the center, I am sure tensile forces play a part also but that side to side is what finishes them off.

Not to belabor the point, but are you sure that the exhaust flange moves from side to side at the ends but not in the middle? It’s a solid piece of steel and the heat will influence it evenly. I think the end bolts will be stressed slightly differently due to their location, but not in a shear mode, enough to break them.

I am 100% positive the bolts on the end experience more sheer stress than the ones in the center. If the ones in the center move .010 side to side then the next ones move .020 side to side and the end ones will move .030 side to side (ball parking for simplicity sake as it is probably not mathematically exact) because they experience the expansion from the middle PLUS the expansion from the additional length between them and the middle.

i was just thinking about the K car exhaust that had a spring between the manifold pipe flange and the retaining washer and nut.
i wonder if this would be anything to contemplate...........
a longer bolt of better material, a spring close to the shoulder length of the bolt [longer or shorter length of the spring, i can't say] then the cone washer [?] and nut.
just a musing thought rolling around in my noggin.

Well, I couldn`t get two of the bolts out of the drivers side. When I tackled the passenger side myself the broken bolts cam out with the welding a nut trick but these two on the drivers side were broke off too deep. I ended up taking it to a local shop. They had the truck for two days. The said they ordered a special tool for drilling the bolts out. All back together now after $700 . YIkes!

They typically don't break too far down and they generally are not hard to twist out, if they break off flush or just below flush I take a cut off wheel and cut a slot in it (might get the head a little bit so make sure your not aiming your slot toward the port or you'll make another leak path) so I can use a flat tip screw driver to unscrew it. The screwdriver it's elf I will make super flat with a stone of some sort so it bites into the slot real good as the slot comes out slightly rounded in the bottom.

I wonder if any Toyota, BMW or Mercedes exhaust manifold bolts are the same metric size and thread as 5.7 V8 exhaust manifold bolts?

Used that method recurrently and if it did not stop the problem, did a few other mods involving relieving the hole/slot in the manifold casting to provide additional expansion and also taper ground the outward face of the manifold ever so slightly (thicker at the ends and thinner toward the center). The concept of using the bronze is the softer metal allows the cupped washer to slide under heat cycling (put some graphite under the washer).. A few cases I've actually filed the cupped washer to provide a "flat" rather than a cutting edge.
On some motors we have even gone to soft steel studs with a small nick with a hack-saw to give the studs a spot to break above the head surface.
Lots of little movement ultimately breaks steel that is subject to frequent heat cycling.
Some things are impossible to stop (look at aftermarket 4.0 l jeep motors and their aftermarket accordion tube steel manifolds}. Control or allow for movement is key.

Had it happen twice to my 2012 Ram, went to a stainless shorty header and it hasn’t happen again.