1. Only way a turbo can be lower then the oil pan is if you have a pump which pumps oil from the turbo back to the engine. The oil will not travel back up the line to the oil pan by the engine's pump alone. Eventually it will puddle up, may leak and/or blow out the seals on either the turbine or compressor side if not both. This is turbo kit design 101.
2. Putting a single turbo where the air box is will be fine. Don't take my word for it, just go over to LS1tech.com and look at all the turbo kits that were/have been made for the Fbodies. Some relocate the battery to the back and place the turbo there. Some put the turbo between the crank pulley and the radiator. Some, like mine, relocated the alternator to the driver's side(think LS1/LS6 vettes) and place the turbo where the alternator was. Heck, look at the STS kits, the turbo takes place of the muffler but its also designed to run back there with smaller exhaust housing and some guys have coated/wrapped their exhaust pipes/headers. Think they don't work, please go to LS1tech and lookup Zombie and a few others like him. He runs 10s @130+ in Las Vegas in the summer time with a home-made rearmount kit. I've not only seen his car run, I rode in it and let me tell you, for a street car, its bloody damn fast. "blueflag:
Honestly, turboin' your Titan would kickass! One word of advice, no matter how many times you run the numbers of how much it will "cost", add at least another 30% on top of that for things you go "crap, I need this/that/other thing". It will save you a lot stress and frustration. This is coming from someone who has been around Forced Induction since 2001, small time here..:jester:
I would love to turbo my Titan but I have other responsibilities to take care of first before I even think about it. That and my wife would probably shoot me if I made my truck into toy #2. :jester:
I would advise anyone who wants to get into turbocharging to pick up "Turbochargers" by Hugh MacInnes. It's a good read and very helpful. Good luck and I'll keep looking for your buildup thread.