Your hand goes between the turbo and the cowl(part of the truck that sticks out from the fire wall over the turbo). Also the little orange boots that connect the intake "Y" to the intake plenums: if they are 2" it is an early99, if they are 3" it is late99-03.
If you take the valve cover off you will find a part number on top of the injector. You do not have to take the injector out. there is no other way to find out what injector you have without taking the valve cover off.
If you have forged rods you need to do some inspecting of your truck. To see if you have forged or PMR's follow the instructions here:
7.3 Inspection Hole for Powdered Metal Rod Determination
If you have PMR's max power is 400hp but if you have forged rods then max is somewhere from 500-600hp.