there are some assembly line pics in the Bunn books that lead me to believe the suspension, powertrain, and steering are installed to the chassis; the doghouse etc is set in place; then the cab with full doors is installed over the steering wheel; then the bed. In these pics, there may be special tooling used to set everything in place so that all the parts line up, especially the cab. I learned the hard way that the best approach is to put the cab, fenders, and hood in place with finger tight hardware, so that adjustments can be made during installation without too many tools.