87 Crew Cab 454/TH400 to Cummins/NV4500

[jltait]

Hi all been lurker on this site for awhile but this is my first ever build thread, on this or any site for that matter. I have had quite a few projects, but never really documented them well in the past. I will try to lay out as many details as I can as I move forward with this project. I have been hit and miss with pictures but I will put all into this thread. I struggled to find some of the details of this conversion so I will put as many as possible in this thread to aid others who are doing or plan on doing this or a similar conversion.
The reasons for the conversion is first for mileage, I have had diesels in the past and wanted to get better fuel economy. Secondly the 454 had a couple issues that needed to be rectified, namely a bad rear main or seemingly rear main oil leak and a cracked (nearly in half) exhaust manifold. Considering I had the Cummins engine hanging around in my garage for some time now and a 454 with the issue outlined making this conversion happen just made sense to me.
Jason

The truck