Sorry in advance for the crappy pictures and rough instructions. Probably only Dim_Reapa will care about these, but putting them here so I might be inspired to improve them.
KEY: Make sure the bed details are facing up. Turn the parts above into the structure below. If the holes in the acrylic bed are too tight, they may need to be filed or cut out a little. Note the pieces are not glued in the picture below, you probably should glue them.
Use the parts below to add to the builds in the next two pictures.
Alternatively, the wide front part could be used, or the taller engine compartment sides could be used too. Either way, the front part will require some trimming and fitting to fit the two hood pieces.
KEY: Make sure to put the big hole of the larger side of the cab and the small hole in the top over the smaller side. The slots in the cab top are so that the visor can be bent down to the desired angle and a bead of glue can make the angle permanent. The thin white card top can be glued on after to give a smoother look to the top.
Various pieces can be used for the front and back skirts, and the thin white card pieces can optionally be used for the side skirts. If I included big dowels, the can go on the sides between the front and middle axles to represent fuel tanks, see 396 as an example below.
The cab side shows some slots for the exhausts, and the wire can be used to connect to the bottom of the exhausts. The engine compartment side shows where the air filter brackets fit and the hole for the wire to go into the side of the air filter (the short wooden dowel piece.) A small disk and a larger disk can be glued to the top of the dowel to give the classic air filter look (see below for an earlier generation built version.)
Turn the pieces below into the undercarriage. Don’t worry about the undercarriage having so many holes, they will not be visible once the back and front pieces are installed. Painting the deck will high the rest.
The icons and armor plates cut from the thin white card can be applied as desired. Choose a front grill that you fancy and add headlight bits as needed.