So, this really belongs in the conversion forum, but here you go:
7.3 PSD uses Ford 385/335 Series bell housing found on 370/429/460 big blocks and 351M/400M intermediate blocks for both manual and automatic transmission applications. Reports that these engines use the Modular pattern exist across the Internet and on Wikipedia, but you can't trust Wikipedia as a source and I have put eyes on many a 7.3 PSD with the "460 Ford" bell housing pattern.
6.0/6.4/6.7 PSD Automatic uses Ford Modular Series bell housing for all automatic applications.
6.0/6.4 PSD Manual transmission applications use an SAE pattern the same as the International/Navistar variant of the engine.
Now for the bad news. You will destroy that transmission behind even a Van spec 235hp 6.0 PSD. Also, there is no 6.0 PSD manual trans flywheel small enough to fit in the Modular bell housing pattern. Making a custom flywheel will present a huge challenge to fit a disc with the correct inner radius to work with the rear crank flange pattern. Alternatively, you could completely disassemble the engine, remove the rear adapter flange from the crank, and machine one that allowed use of a Modular flywheel, but either way, you're doing machine work.
Your best bet would be to use an automatic, like a C-4 or a Powerglide in a hot rod 6.0/6.4 or even 7.3 application, I'd go with the glide myself, all that torque, a trans that can be built to handle it, etc.
If you're dead set on using that transmission in that truck, maybe look for a cheap 6.8L V-10 with harness and computer. The 2002-2005 2-valves will make 350-400hp at the crank with intake, headers, exhaust and tuning. The later 2005-2010 3-valves can make 400-450hp at the crank from intake, headers, exhaust and tuning. Either of those V-10s will eventually break that Tremec 5-speed though, and even for the V-10 I'd strongly suggest a Mustang Cobra T-56 or Shelby GT-500 Tremec 6-speed against the weight of your proposed application.
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The Current Truck (Oct-2013 to Present):
1999 (Early) F-350 Lariat, CCLB, SRW, Black/Tan
7.3L Powerstroke, 4R100, 4x4, 3.73, 37x13.50-18s, '05 Axle Swap, 6" Fabtech lift, GTP38 "D66" turbo upgrade, SCT 4-position chip with custom tuning by me, Straight Piped 4" down pipe through 5" dual stacks, N-Fab full length triple steps, Pro-Tech cab guard and tool box, louvered 5th wheel gate, Hella 500 Fog and Driving lamps, much more to come...
The one I'll miss, (Mar-2009 to Jan-2014):
2000 Excursion XLT 4x4
6.8L V-10, 4R100, 4.30, 285/75-18, 271whp / 388wtq
The one I won't, (Jul-2005 to Sep-2012):
2005 F-350 XLT, CCLB, SRW, 4x4 FX4
6.0L PSD, ZF-6S650, 3.73, 35x12.5-18, 4.5" Lift