Alex, can you pass on to Bryan that once you start getting into larger sized trucks, US heavy truck Manufacturers start to move away from specific brand bellhousing patterns and use "SAE number" bellhousings. There is probably no adaptor fitted to install the diesel in place of the petrol motor. SAE 1, 2, or 3 are the most common truck patterns.
I will send a word doc to you Alex with the SAE patterns.