So I got the speedometer from belair2door on ebay per 72duster440's suggestion. Pulled the old one hooked up the new one. Speedo bounces all over the place randomly but also consistently shows I'm driving 20mph faster than I am.
This never happened before. I haven't changed tire size or any of the gearing. But I did hand spin the speedometer while cleaning it back when it was out of the cluster. I dunno does this sound like I need a new speedometer gauge? I know they aren't cheap.