Speedo stops working

[89prerunner]

Just bought an 89 ranger for my son. The speedo intermittently stops working while we are driving. If we are in overdrive, it downshifts every time the speedo cuts out. Haven't pulled out the guages, but the transmission side of things appears to be hooked up correctly... doesn't bounce before it shuts off. seems to work ok when we first start driving, but then after a while it just turns on and off when it feels like it. any thoughts?

 

[hopster]

being an intermittant issue i would start looking really closely at all your connections. and see if hitting the cluster can cause this to happen or return it to normal when it does happen

 

[89prerunner]

tried tapping on the guage cluster, but nothing. I will try the back of the guages when I get some time.
Any idea why it would impact the shifting of the transmission? It locks out the OD when the speedo is off.