When I removed my 6.1L intake, all of the original plastic bushings were broken. The 6.1L intake manifold bolts are not avail any more from Mopar from what I can see, and all of the aftermarket bolds do not have the bushing or a proper shoulder from what I have seen either. This is how I solved the problem. Fig 1. I bought 11 of these metric bushings from Ace Hdwr for $0.30 ea. Fig 2. Use a 6mm threaded rod or bolt to roll the bushing on in order to make it easier to cut (use a glove). Cut the bushing in half as shown. Fig 3. Test fit bushing on bolt. Fig 4 & 5. Install the bushing into the manifold.
Original bolts could well be torque to yield (TTY) due to securing aluminum manifold and may need to be replaced.
You may be right, but that is unlikely as the torque is less 108 in-lbs. That is less than 10 ft-lb and not enough to distort the bolt.
There are a variety of potential issues involving Dodge intake manifold bolts through a variety of current displacements. Torque spec on the video application is also less than 10 ft lbs. I've recently broken a reused bolt of similar capacity just snugging it up (thinking it unlikely while applying such a minimal amount of torque). Bing Videos
Galling can occur more frequently in some metals. I think aluminum and stainless steel are more prone to it than carbon steel. That can make it easy to break bolts. No pun intended, but I'm a little rusty in my metallurgical knowledge.
I ended up using white rubberized screw end caps. They fit perfectly over the intake manifold 6mm course thread bolts and are the proper diameter for the manifold collared bolt holes.
I've read reports of the 5.7 intake manifold bolts working themselves loose and that Dodge discontinued use of the 6.1 aluminum intake design due to a propensity to overheat compromising it's (and it's bolts) integrity (ability to remain sealed and to be resealed). My metallurgic knowledge likely falls well below yours.