I Have A 71 El Camino With The Sweep Speedo Dash. I Want To Change Over To A 71 Ss Tach Gauge Dash , Can My Exsiting Wiring Harness Be Adapted To Work ? I All Ready Have A Set Of Underdash Gauges Hooked Up, Tach, Amp, Temp,oil, . Can't I Use Thease Connections On The Ss Dash .

Need to find a 12 pin SS gauge connector (many 70's camaros, trucks use it). Leave enough wire to splice into when you cut it off. Then use the info from this URL to wire it up. http://www.azendrud.com/gauges/gauges.htm

I did the same thing on mine way back when and salvaged the plug-in (keep a long pigtail like Steve S said!) from the donor dash (idiot light dash). It's pretty easy to xref and splice into the plug. The printed circuit is the one to be careful you don't tear it or anything. The plastic on mine tried to separate exposing the copper circuit. Once it's broken you have a problem. I replaced the idiot lights with autogauge minigauges (behind the panel as orig) and wired those directly and it looked great and worked great. If you are trying to use original gauges, you may have trouble if the sending unit is different. In my situation I bypassed all the orig sending unit wiring. I wish I had one of those dashes for my current Chevelle and I'd do the exact same thing.