Thanks guys. The reason that I asked is that Brothers lists a harness for a 1978, and then a 79-80, and I'm not sure what the difference is between them since they seem to look the same to me.
Maybe the plug on the backside of the tach gage is different? That's why I posted a pic of the backside of mine. I could make my own like you say if need be, but I'd like to get the right harness that would just plug up if I can find out which of the two that I would need to order from Brothers. ...Joe
http://www.brotherstrucks.com/products.asp?dept=748