AJ, the only way I could tell you if your engine is out of a 2WD or 4WD vehicle, besides a picture or two of the oil pan, is to ask is the pan more smooth or rigid (like with a guard on it) at the bottom? Also, is the oil pan made at a 90 degree angle at some point on it? If it is then that will tell you it's an engine out of a 4WD vehicle because that 90 degree angle is supposed to sit right in the motor mounts and clear the front axle just right. If you were to see one installed in a 4WD Isuzu you could tell the oil pan is just made perfect to go into the 4WD frame/chassis. Otherwise if the pan is smoother looking it will be out of a 2WD for the most part. Are you able to take a shot or two of the oil pan for me? If so I can tell you what it's out of. As fas as any other insight, do take a visit to
http://www.4x4wire.com as it's a good website that deals with Isuzus pretty heavily and has its own Isuzu Diesels forum. Hope this helps.
Salvy