The first thing to do is find the fuel gauge wire that runs to the tank. Ramblers usually have it in the trunk, a yellow wire running through a grommet in the trunk floor near the front, usually on the driver's side. Should be a connector close by. Unplug it then ground it. The gas gauge should read FULL when the wire is grounded. If the gauge doesn't move at all the wire may be broken. There is a big connector behind the left kick panel. Find the yellow wire there, unplug, and ground the end on the dash side. That will eliminate the wire running to the back. If the gauge still doesn't move, check the temp gauge the same way (except it doesn't go through the kick panel connector). Disconnect from the sender and ground. Should read at the top of the HOT end. If it doesn't, then the voltage regulator behind the cluster is bad. See http://www.wps.com/AMC/dashreg/index.html
for the best replacement.
If the gauges both read FULL/HOT, then you have a sending unit bad. you can get a replacement unit from a Rambler vendor (www.ramblerparts.com
, several others). Or you can modify a universal part to fit. You need one with a 10-78 ohm range (empty to full). This one works: http://www.jcwhitney.com/adjustable-...09&filterid=j1
What you do is unbolt the unit from the adjustable mount and just use that. Drill the rivet out of the wire stud on the original unit and use a small brass machine screw and nut for the wire on the new unit. Pry the case off the original unit, leaving just a metal plate on the pickup tube. I got one screw through the slot and used a washer on the other one to clamp the new unit to the plate. It can be wired on also -- plain steel wire won't rust inside the gas tank since it's usually immersed in gas. Cut and bend the float arm to match the original.
While you have the unit out of the tank replace that old strainer on the end. It's a 5/16" pickup tube. A strainer for a 65 or so Mustang is perfect and can be easily ordered through any Mustang supplier -- auto parts stores may have it since it fits several early to mid 60s Ford products and should be popular enough for them to at least keep in the warehouse.