Fuel gage and speedometer need work

A quick and easy check of the sender, is to remove the pink/reddish wire, and touch it directly to the black wire. If this pegs/moves the fuel gauge (with the ignition switched on) then it's likely not the gauge and more likely the sender.

Randy,
If the fuel gauge is off, then yes the sender may be bad. You can pull it and get Ohm readings as you move the float (it's a linear reading) but by then you might as well put a new one in. Make sure the tank is well grounded. Pull the ground wire off the tank and Ohm it out to the engine block. You should get a near zero reading. Extra resistance to the sender will give you low gauge readings. You will also need to Ohm out the sender wire between it and the gauge. that too can add resistance typically from bad connections. Also make sure you have a decent 12 volts to the gauge. A good cleaning of ALL wiring connections would be a good idea.

Your speedos run on air so any leak between the pitot on the gauge is a problem. Yes, the pulsation dampers on the transom can leak. If the pitot was plugged and the damper had water in it and then froze, they will crack just like a copper pipe in your house. If it's cracked, treat it the same as a copper pipe and sweat solder a patch onto it.