73 Dart Swinger. I am going to replace the fuel gauge in-tank unit. The FSM show a spanner wrench that I obviouly don't have to remove the lock ring. First of all, is this pretty tight and hard to get off? Before I start trial and error to find the best way to remove the lock ring, I thought I would ask y'all what you have used. Or should I Just go get the proper tool to make my life easier. If this is the case, are there adjustable wrenches that would work for this?

Also, I was just going to do it with the tank in the car. Once under the car, there seems to be enough room to do this without dropping the tank. What do you think?

Use a brass drift to turn off the lock ring.

Hi,
Eric is giving you the truly practical answer...but if you want to try the tool try this: THe Ford wrench works and you can easily copy it and make one with a grinder. Look on ebay for something like Ford sender wrench or the like and you will see a maltese looking thing. I just ground a piece of scrap to fit a cardboard cutout and brazed a 1" nut onto the center. Of course, what Eric is saying is easier...a brass drift and a few whacks, but if you want the tool....
rock
'64d100

I taped a rag around the tip of a big screwdriver so it wouldn't spark.
Gave it a few good taps and it came right off.