What is the most expensive parts of trucks?

Engine is the big one that hurts most people, anywhere from 15 to 35k is normal, 40 to 50k dollars isn't unheard of. The good thing is that is a usually once in 6 to 10 years expense unless you're running the wheels off the thing. Transmissions and rear ends can be pretty expensive too. It's all the "little" stuff that doesn't look like much at the time but adds up. Brakes, radiators, hunting wiring issues, tracing air leaks. They're a pain but don't hurt as bad as it's usually a grand here and there not 5 digits all at once.

 

Most auto transmissions are just manual transmissions with a bunch of electronic crap added on to shift it for you. The base transmission and clutch is the same. Only added cost would be the electronic parts bolted onto it.

 

Engine.
Second Probably replacement of entire DEF system

 

Repair is a pretty broad term too. Complete engine rebuild can hit mid 5 figures. Other engine repairs could be anywhere from a couple hundred bucks to a couple thousand.

Aftertreatment system is probably the most tempermental system on a truck.

 

SCR system,
The DEF filter is like $2500-5000
But the entire system could be outrageous.
Even on diesel pickups.

 

Just a DPF and DOC on a little skid steer loader is around $2500 AFTER returning the cores.

 

I Did an inframe last year on 2009 isx, with new water and oil pump, and new ac compressor and new clutch/pressure plate/throw out bearing since it was 5 years old, while it was down.
Was $22998.50
That was before the now parts shortage