You don't need a rallye dash wiring harness. You can modify the the stock harness. You will need to take the oil pressure idiot light and cut it off. You will use the grey wire from the idiot light to connect to the oil pressure gauge and I believe the other wire is used as power for the clock. Then you need to run new wires for the tach. Everything else should be fine as far as wiring goes, all of the wires go in the same spots on both standard and rallye gauges. It would be better to install the rallye gauge light panel with the four lights instead of three, but not necessary if you don't have it. As stated you will need to change the oil pressure sender in the block, most auto parts stores have them in stock and they cost about $25 I think. If you have removed e-body instruments before, it's the same thing just with installing different gauges but they go in just the same. Sorry I don't have any pics, hope this helps and if you need any more details just let us know.
