If you haven't cut/spliced the alternator connector I believe I'd maybe consider a conversation with these folks for a harness.
Scroll down to the W3030D and that is correct for the car harness, ask them if they can assemble you a short harness to your requirement. If you need some additional length they can accommodate you. No cut/splice solder and no aggravation. I'm quite surprised knowing the $$$$$'s you paid DC POWER that they didn't accommodate you. It's attention to "detail" that finishes a project and I'd think they came up short.
http://www.qualitypowerauto.com/item...-Harnesses.htm
I believe the Denso plug is a 312 but I'm sure these people would understand and you've got you snapshots.