Pressure wash for what... just slinging crap all over and in the air?
I had a vehicle so bad it sucked to sit in and move...
Took apart the entire cab, steam cleaned the small parts (dash cluster, steering wheel, etc) hose washed the inside, used (not at the same time) simple green, purple power, orange cleaner, glass cleaner w/ amonina (I was trying to get stuff to sanitize that was not like bleach and deodorize that was also cheap the orange cleaner and glass cleaner.... dollar store) and a scrub sponge. I also steamed (what was doable) smaller areas in the the cab (areas hard to scrub mostly what would be behind the dash) to everyone's amazement when I was done. Truck has 0 smell. It took alot of time, *alot*. I also used simple green in the steam cleaner... YMMV. Truck was bad was sitting on a farm, used a tire brush to wash the MOSS off the truck...
For what you asked, nothing is really in the cab... the dash bezel has screws you can see, the gauge cluster is a bitch you need to d/c the spedo cable while it's in... and the dash is clips / screws. That's pretty much the entire inside... just take stuff apart slow and as said, remember its 35 year old plastics... be gentle. Oh seat is 4 bolts...