Challenger

Its probably the power steering pump.

If he is seeing soot on the body paint around the exhaust its probably coming from the exhaust which is a sign of a crack filter or a filter that is leaking around the edges. There shouldnt be any soot anywhere near the stack. Front loaders run with the forks somewhat forward so putting a 90 out to the body could put the exhaust right at the arms, depending on where the driver has them. Its under warranty so it needs to go back to the dealer.

Thats why it becomes the owner's choice. What works for some doesnt work for others.

I second that.

Mack did come out with updated lo, hi split and synchronizer parts this year. Get the Mack parts, the generic aftermarket parts wont last. There was also a service bulletin saying you have to replace the synchronizer fork pinch bolt. They say the bolt has a scotch lock on it and can only be used 1 time. Even if you use loctite and torque the bolt it can back out and cause synchronizer failure. Im sure there are alot of mechanics who reused that bolt and caused premature failures after their repair. The main 2 Mack Granite trans failures I see are the pinch bolts coming loose around 60,000-70,000 miles. I assume this was a factory defect. And the other one is transmission cooler failure. The cooler fails and allows coolant to flow into the trans and basically wipes it all out. The other reason are improper repairs. I just repaired 5 trans from one owner. He had a guy who knows Mack trans repair his trans. He did half ass repairs with aftermarket parts. 2 of the trans never made out of the garage.

I dont think Ive ever seen a Midliner not smoke. Very interesting

All MRU's and LEU's have that same stack, there should be no reason to change it. There are 1000's of the same trucks out there running just fine with the OEM stack. You do have an unusual problem that will require a dealer service with Mack tech support. Is there any signs of soot inside the exhaust pipe or around the exhaust? I would think that if exhaust is coming form your stack it would be visiable on the white paint. There should be 0 signs of soot anywhere. Anys signs of soot means the DPF filter is cracked. Assuming there is no signs of soot around the stack they might just replace the air filter, repair/replace the air intake, let you run the truck and keep an eye on it.

Im going to guess and say the original owner may have broke the lever off to keep drivers from driving it like a 10 speed and tearing up the back case. People get in a truck with a lever on the shifting knob and think they have a Hi and lo side. This trans does not have a synchronizer. Every T2060 I see has a failure in the aux case because of improper shifting. If lo reverse and lo 1st arent needed I would leave it in high and drive it like a 5 speed. Ive taken the air shift lever and airlines off by owner request just to prevent future failures. Even if the owner is the only driver, somewhere some mechanic will get in and attempt to shift it like a 10 speed and start the failure. Sounds like the previous owner paid for trans repairs due to improper shifting. Its a simple costly mistake that WILL happen.

Have you checked the fuel and boost pressures?