Autometer Electric Speedo Issue

[esents]

I have a 91 s13 with a redtop. I an having trouble getting my autometer electric speedometer to work. I believe it is the "Out" port on the back of the speedo that I have wrong. When I hook it up the speedo pegs at 160mph and the odometer starts ticking up quickly. I am using the autometer speedo sending unit. Any advice is greatly appreciated.

Thank you all,

CM