To put it simply, the same way you took it apart. I dont really think you will get two people to answer this question the same way. Do what makes sense to you.
For me, I would set the engine (on completed chassis), set the cab and then the steering gear/mast. Then, it is in whatever order makes you smile at the end of the day.
Edit: Oops, I assumed an AD truck, might not be the case.
Last edited by DavidF; 12/24/2012 8:54 AM.