Why would you get your harness reworked
 

This might be a dumb question, but I cannot find any reasoning other than "because" to have a harness reworked. I have a 2010 Chevy Express van (l96/6l90) that I am using as a donor car for my 74 nova. What do you remove from your harness and why? The most common is the secondary o2 sensors, which I have been thinking of buying some cats to help the car run cleaner. I understand wanting to get rid of the vats, but what else would need to be reworked? I was just looking to see if I was missing some reason behind removing a lot of things.

Also, has anyone used gauges from their donor car in their car? I am thinking of using the gauges from my van in my nova to have physical gauges then building an aux gauge cluster with a raspberry pi that will pull data from the obdII port. (I am a software developer so it will combine my love for cars and coding), but I just didn't know if anyone has used those gauges. My main worry is the size and I am pretty new at fabrication. I am assuming the gauges are on one pcb so I would either have to make a new one or enlarge my cavity I have for gauges.

There are a lot of connections that are related to the donor vehicle that are just not needed and add to the tangled mess. So they are removed.

Gotcha. Thanks. So what I was reading on lt1swap was correct. It is for that clean look not necessarily for a working car.

You can cut the plugs off and consolidate the hots and grounds and remove vats and run the engine. When you rework the harness you loose a lot of bulk and extra plugs. I also took time to reroute my harness like a car harness so the bulk is behind the intake. I ran the DBW and front sensors under the intake.

look at harness rework videos, diy ls harness, 4 wire harness videos, etc on youtube. youll clearly see the amount of crap in the oem harness that's not needed for you swap. I am doing my own harness, I have so far removed no less than 7 connectors and 24 wires. probably more. but other things to consider, ive added egr pins to my ecu plugs and ran those wires to my wideband 02 sensor so I can monitor it with hp tuners on the stock ecu. ive also pinned in wires for flex fuel sensor my harness didn't have as well as changed the injector plugs to more common ev1 style, changed map sensor pigtail to a different style, deleted rear 02s, maf and converted to IAT sensor, extended coolant temp sensor and alternator wires so they can run down the one leg off bank 1, deleted second trans vss and neutral safety switch plugs, etc etc etc. finally ill be relomming the harness to a much better and nicer looking braided split loom. so a little bit of function as well as appearance changes are being made. all this cost me about 200 bucks ontop of the harness due to new sensors and pigtails needed plus quality shrink wrap and loom being used. I don't want to due this twice :)