That depends on how you removed the IP.
If you removed the IP from the IP drive gear cover and left the drive gear meshed with the cam gear and the IP drive gear cover installed you are already in time with the gears.
The dowel is part of the IP drive shaft, it will only go in in the correct position.
If you removed the four bolts holding the drive gear cover and lifted everything off the job just got harder.
Try these directions.
If you change the IP, the important thing is DO NOT REMOVE THE IP DRIVE GEAR COVER.
Remove the air cleaner.
Remove the two bolts holding the plate below the oil fill spout.
Then remove the three 5/16" 12 point bolts that hold the gear to the IP drive shaft.
Remove the wires from all three electrical connections.
Remove the return line from the fitting on top of the IP.
Remove the fuel supply line from the filter header to the IP.
Loosen all the injector supply lines at the injectors.
Unhook the throttle cable frojm the IP.
Now remove the three 9/16" nuts that hold the IP to the drive gear cover.
Work the IP toward the rear, tilting the rear of the IP up as you move it back.
With a little finesse you should be able to raise the rear of the IP with the injection lines still attached.
The entire IP and injection line assembly should come out in one piece looking like a butterfly.
Does the new truck have a turbo on it?
The turbo does make it harder to remove the IP, the passenger side injection lines and the turbo need to be in the same place at the same time, but it can be done.
After it is removed, notice the alignment dowel on the IP input shaft.
Look where the slot for the dowel is on your engine, turn the shaft so they will line up when you reinstall the IP.
Care should be taken to not unmesh the IP drive gear from the cam drive gear, that throws the injection timing off.
To many people remove the four bolts holding the IP drive gear cover down and lift the gear, drive gear cover and IP out together.
Getting the gear back in the right place is tricky without removing the front of the engine to see timing marks.
Install is the reverse of removal.