I just came back from a long weekend of mudding in VT. I have a question about what seems to be loud grinding type noise during engine braking on 2004 Rubicon. Its hard to pinpoint but it sounds like the noise in from the 424 shaft? It doesn't do it everytime, and its a very different noise than the standard noise it always makes during engine braking. Also when it happens, I can stop on the hill and roll 6" and it will make the noise, which can't be engine brake in my opinion. I rode the bike basically the same way the week before when I first installed the 424 and never heard it, this week I installed a new Disk brake conversion kit and it works great, it doesn't sound like its from the brakes but I'm a little stumped if anyone has any info I appreciate it. I was wondering if its could have been related to the mud? maybe caking up somewhere and was sporadically making it wobble or something?