Anybody swapped in an LS1?

[Russell]

The DRAC is just a little yellow or clear module back behind the dash somewhere that converts the signal your transmission makes to what your speedometer can use.

You'd basically need the two wires that run from the transmission's speed sensor to the DRAC, likely along with a power and ground wire, then run the 4000 ppm output to the speedometer, which would also need a power and ground wire.

The DRAC probally has another output for the electronic cruise control setup, but you won't need it, unless you are retrofitting cruise in as well.

The PCM would need to be hooked up to the two wires that run to the speed sensor as well, its fine to splice them all together, as neither the DRAC, nor the PCM should be changing the voltage the sensor produces at varying speeds.

I don't have a DRAC on hand to take a picture of, but if you pop over to www.fullsizechevy.com, and search for DRAC, you'll find gobs of pics, and probally wiring diagrams / pinouts as well.