Christian,
I have done this several times. My suggestions might not be the best, but this has worked for me.
If you have not yet painted or chromed your grill pieces, spend some time "dry fitting" all the pieces, bending and shaping the mating edges until they are tight. Also note that screw/rivet holes often become deformed and have to be flattened in order for mating surfaces to come close together.
Next you have to decide what type of hardware you want to use: rivets, machine screws, nylon or metal washers, plated steel or stainless. Chevy Duty has a good hardware installation kit (if you want standard rivets). I found that I could not get a rivet gun into place for a tight rivet, so I used machine screws. Other people who have posted on this site have had good experiences with rivets.
Lay out all you parts on a carpeted floor and start to put them together. As I recall (the last time I did this was last winter), I started by putting the "nose" on the bottom piece of the grill and worked upwards. I might have attached the parking light panels to the middle cross bars before I attached those bars to the nose. I have done this myself but find it safer and easier to work with a helper.
Once you have the grill together, it can be installed onto the fenders as one piece. I have done this myself but only when desparate - find a friend or two to help you..
Make sure you have enough spring "nuts" (I think that is what they are called) and screws and flat washers. I used large-diameter fender washers wherever they could fit - and wherever they did not show on the outside.
The grill/radiator shroud should not yet be on the truck.
Gently fit the grill against the fenders and line up the upper fender holes - attach the screws but do not over tighten. I do not have the exact number, but I bet there are around 30 spring nuts that attach to body panels and screws that attach the grill to the spring nuts.
Once you have all the screws/bolts in place, I suggest that you install the (bumper braces, if they are not on already) the front valance, and the front bumper. This will allow you to adjust alignment.
You might find that you will need to loosen fender bolts (to the radiator frame and to the fender braces) in order to get a good alignment of parts.
Maybe other people will correct and clarify my instructions.
Good luck,
Tim
