@AH64-longbow Peter,
Long read for just a few questions. If you are a welder and a helicopter pilot, you are more than qualified to fix all of the short comings of this truck.
1st remove the washer or slice it off and or move the roller arm for the air switch to where they no longer meet and auto 6x6 is no more, it should not have ever been put on these trucks. It is the reason for busted transfer cases! The front or rear will slip and then all that huge amount of torque will just rip the case in half. Never use 6x6 on high traction surfaces something will slip and cause a breakage. Might be your case making that grinding sound already
2nd your tire size is helping lots. Go methodically though adding engine upgrades add the gages first! Then intercooler, get rid of cobrahead at turbo and then up injection timing, then fuel and RPM adjustments. Do those in order and you engine will be much better and very easily handle the roads and loads. BUT your transmission might not I would add a additional transmission cooler somewhere it can bring temps way on down.
3rd definitely do the mod on the dogbones to prevent them from popping off. This may save you many headaches.
4th please be careful fixing those spring brake cans. Make a guard to go around them and hold them as you let off the pressure and to reassemble the cans. You can also leave the covers off the backing plates to help with cooling and mud removal and pad inspection.
5th change the other side u-bolts and trim the excess off. They probably will let you down also because of stress at the other side breaking.
