[special-K]

I don't know a lot about the NV4500 and NP241, but I had a lot of experience with troubles in both K3500s I had with that combo, a '92 and a '95. One issue in both was the DMF flywheel, which I have three different works for that acronym to call the engineers that thought that was a good idea. Both trucks ended up needing a swap to the trouble-free tried and true solid flywheel.

In the '92, I had already replaced the NV4500 with a GM crate due to dropping 5th gear resulting in expensive internal damage. To add insult to injury, later on the rubber cushions in the Dumbass MF'r gave out. GM didn't even sell replacements, but they did sell the parts to swap back to the smarter design. Before I figured out it was the flywheel cushions I thought it was a bad input bearing and had one on hand. Got into it, found the problem, and got the parts to go solid flywheel and that required changing the input shaft and a different input bearing. I guess that is the difference in input bearings kwmech mentioned above. That is my guess.