Research is the key to any build, find photos or take them yourself, and replicate what you see, and generally if it looks right then it is right, so keep referencing your pics
just remember when you plumb or wire something, it should stay in scale to what the real truck is, for example 1mm (0.40) wire x 25th scale = 25mm or 1" not many if any brake lines or suzie cords are 1"
so what you can do is strip the cover off it, which is getting closer to the true scale of what it should be, or use nylon fishing line for things like air lines, detail nuts etc can be cut from hex rod, lots of photo etch stuff is available, as well as manufactured nuts bolts washers, rivets and the list goes on
also ink is a good thing to use for oil stains on engines
Dont be scared to take as many reference pics as you can

You can build anything you want if you break it down into parts, or pieces
real air cleaner

one I am playing with


and the tooling to make it

and you can use most materials
Aluminium

Plastic

Brass

Certainly the key is to have a go, do be afraid to try things, and if it doesn't work, try something else,
Yes by all means post your builds, I am sure a few here will be willing to help