24v to 12v conversion help needed

[beee]

I have a 98.5 24v cummins 5speed, It has a cracked block and a bad lift pump, probably bad IP, so I would like to do a 12v swap. To have a fully functioning truck, cruise, check engine light, stock gauges, etc what are my options?

1. I have read that I need a 98 pcm, but wouldn't there be more then one part number for 98 pcms? I could see there being different ones for: (auto/manual), (cruise/no cruise), (California, non cali emissions) (air conditioning/ or no a/c). Is there a part number list? Am I wrong is it much simpler?
2. What about a 97 pcm, would it not communicate with the other computers and instrument cluster?

3. Which harnesses do I need? I read I need firewall forward which is 2 separate harnesses? One is an engine harness, and the other is what the fuse box? Can I use 97 harnesses or does it have to be 98?

4. I shouldn't have to change the instrument cluster or any in cab harnesses correct?

Any help would be great because getting a complete donor vehicle is very unlikely and I will have to piece it together probably sight unseen via ebay. I would hate to by parts that aren't compatible.

[bjytech]

I'm not sure on the PCM but from what I've read on the subject you would need the 98 12v engine harness as its different from the 94-97 engine harness.

[beee]

Alright that matches what I have gathered as well. I just picked up a 12v tonight, so I am now committed.  I will probably do a write up when I get the bugs ironed out.