A few years back I changed my cluster out to a 140 Chp 88 cluster. Ever since the speedo needle has bounced around at lower speeds and freeway speeds its normal. Is the speedo bad, or could the cable be going out?
Both of your suggestions could be culprit for bouncin needle. But since you just changed out cluster, i would assume that its popped out since those things are such a pain to keep plugged in firmly when reinstalling cluster.
half asleep....most likely the cluster is causing problem. But it would hurt to check and make sure cable is firmly plugged into cluster. Sorry when they are barely plugged in they usually will make small popping noise as they catch every so often so i doubt this is your case.