All of the info on the 6.2 & 6.5 is located in the Member's only area. I believe that the cost of a Membership really does pay for itself many times over.

It does sound like you have a malfuntion in the glow plug system either the glow plugs are shot or the controller (because it is hard to start). The black smoke is not related to hard start (as previously mentioned white smoke relates to glow plug/system failure.) Black smoke is usally an air intake, lack of turbo boost, timing or overfueling problems.
A really simple way to check each glowplug line is to buy a new glow plug and plug it into each glow plug wire one at a time. This will tell you if the controller is bad right away and if any of the wires to the glow plugs themselves are bad. Remember that the glow plug gets really hot and must be securely grounded -- I use a pair of vice grips to hold it and then ground the vice grips.
Good luck
Al