Still working on gauges that will not work!!

I posted a thread awhile back about my friends fuel and speedometer not working. I have finally got a chance to dig in and try to get something done on this but I am still without luck. The speed sensor has been replaced and I do have ground on the middle wire and 8 volts on another wire and the other has continuity up to the cluster. Checked the cluster and it has voltage and ground and the speed sensing wire is good to the speedometer too. Popped the sensor out and got a mirror and spun the driveshaft and made sure the gear is turning the sensor and it is turning too so all I can figure is that the speedometer itself is bad. What do ya'll think??? And to the fuel gauge, We got another cluster and tried it to see if their was any change and well yes and no. The old gauge wouldn't do nothing didn't matter if it was unplugged or grounded or whatever. With the new cluster the gauge will peg all the way out when I unplug the fuel pump/sending unit and then go back to empty when I plug it back up which all I can figure that now the gauge is good and the sending unit is bad. I'm sure the gauge was bad too now that this gauge does actually respond to being unplugged so at least I am making some progress maybe. Any input is appreciated!!!! Thanks Chad