new to diesels.
 

I just saved a 2000 GMC 3500 crew cab long bed from the junk yard. I rebuilt the diffs, new gaskets for engine and tranny, upgraded brake system, air filter upgrade, new bed-doors-hood. It has 162k but the engine is a reman with less than 30k.
Question:
What upgrades could I take on to increase power. Has any one converted the rear diff to a locker?