Your post raises lots of questions. You will have to be a little more clear on the diesel that has been put into your truck. If it came from a dodge there is no littler version, just the I-6. If you truck is in fact a 1/2t with a cummins in it then you can kiss just about all your running gear goodbye. One of us must be missing something here.
Also the '03 diesels are completely controlled by a computer, not an easy swap into a '97 where the computer only controlled the basics. It is more of a monitor than anything, really, no engine control at all. It is impossible to put a computer chip in a '97. A potato chip, yes, a computer chip, no. Thinking of just the wiring involved in a swap like that boggles the mind.
The best advice I can give right now is before you hotrod anything else install a pyrometer so you can keep an eye on exhaust temps. Too hot = melted pistons or Lord knows what else.
Please reply, I'm curious.