I thought I had found the right Ivr and had it saved but must have deleted it. The ones I see now plug into the back of the dash near the fuel gauge but I have no where to plug it in
That's because on your Barracuda, and later cars with Ralley gauges, the IVR is inside the fuel gauge. It must be disassembled to replace the IVR.
By the way, don't bother replacing it with another factory type IVR, get an electronic one as referenced by @Dana67Dart . You don't want to have to do this again at a later date.
Reference these articles for step by step instructions to replace your IVR. Early Valiant Barracuda Club - Gauge Repair RTE Gauge Faq - rte
