Getting back to the 0411 swap
I found that the donor harness does not have to be the same as the main car
All swaps on here have been TPI cars, they can use TPI, TBI, or V6 donor harnesses
The only concern is with factory manual cars as the reverse lights go thru the C100 connector
Swap cars retrofit the automatic wiring and are not affected
This will save alot of headaches for SD TPI guys so they dont have to track down a hard to find and expensive harness to cut everything TPI about it off
S10Wildside showed a cutdown and prepped harness
http://s150.photobucket.com/albums/s..._Separated.jpg
It can actually go ALOT farther so essentially just be a carb harness
This is a donor from a 92 V6 car
Starting on the left and going clockwise
GRD
ALT
Coolant gauge
Starter
Oil pressure to gauge
Tach and coil power
Fan relay
Fuel relay
I removed the brake sensor plug. My brakes are not factory and have no provision so there is no point in wiring it in
I cut and lengthened the relay wires to move them into the car next to the PCM
http://www.austinthirdgen.org/index.php?pid=19
This site was extremely helpful in spelling out the factory harnesses although it left out the 90-92 C207
After alot of tracing I came up with this

Pin G8 is confusing because both the fan relay and ALT signal both join there
The oil switch was confusing because it uses 3 wires while vortec trucks use only one
Here is a detail and how the orange and gray wires can be removed
Im still unsure why the factory made this circuit about 4 feet longer than necessary
Here is a fan relay
These can be salvaged from any 3rd gen V6 (correct wire length) and most 80's GM cars
You do not have to cut up a factory dual fan harness to get these
For the PCM
LS1 and 3rd gen pinouts are plentiful and easy to find via google or forums
The Express van pinout is a bit more tricky to come by unless you were lucky to pull them from the truck forum before they were quickly taken down
Left LS1 Middle my harness Right Express
Here is a condensed version
Even more simple than the factory ECM

R53 was part of the traction control for LS1 fbodys
There was discussion in the truck forums for using with nitrous retard
Use it or not, it seemed too handy to skip
Now for the harness
It is very simple when you think about it
About 90% done, I still need the HO2 plugs
About the vortec harness:
You dont need a whole one
If it is already removed just take the whole thing
For junk yard shopping you can just pull bits and thankfully all pieces can come from the super plentiful 4.3L V6
Connectors needed:
IGN module plug - 4 pin black
Coil plug - 3 pin brown
Cam position sensor plug (distributor) - 3 pin black/white cap
Crank position sensor plug - 3 pin black/white cap
2x flat HO2 sensor plugs - 4 pin black
4L60E and 4L80E connectors are needed for the respective trans used
Note about terminals:
20-22ga wire GM #12084913
18 ga wire GM #12084912

GM parts have gone up extensively
Terminals come in packs of 10 and are $4.30 per unit... ouch
GMpartsdirect is signifigantly cheaper at $1.12 per unit... ouch
EFIConnection is the cheapest at $.50 each
This is the culmination of about 4 months of research, I hope it helps someone
The images are hard to read so I have reattached them
If someone would like an AutoCAD file of the engine diagram, PM me