While the oil pan is out, remove, inspect, clean and replace the oil pick-up strainer. Water pump inspection, cause it is easier to replace while on the stand than when the truck is put back together and they are pretty cheap for peace of mind. I would check and even replace all glow plugs as they are also very cheap to replace. Have an EGT sender put on the exhaust manifold.
" You never, ever, ever go full retard ! "
Kirk Lazarus, Tropic Thunder