Every shop I know of pulls the cab.. It's easier. Not me however. Beyond my capabilities.
What I find amazing (with the cab off and I've seen more than one), is how corroded the engines are...
That is a non issue with my OBS. When I got the truck new, I lined the openings in the wheel wells with rubber sheet. Keeps the stuff off the engine.
I have no emissions hardware on mine at all. I even eliminated the crankcase breather back into the turbo inlet, added a road draft tube. Replaced the turbo pedestal with a delete pedestal as well. Along the way I added lockers front and rear and roller bearings in all the suspension pivots.
Finally, I stripped the horrible clear coat off the aluminum wheels and polished them.
...you can fool some of the people all of the time, all of the people some of the time...but you cannot fool mom.... Captain Penny (Rip)