[munch]

I am in the process of isolating a problem with no fuel reading and in preparing for a possible replacement of the sending unit I tried to look it up on line.  The numbers on the unit are SW and 385C with what appears to be a date of 06/04. 

I was able to locate a Stewart Warner with those numbers, but it has a 5 screw pattern.  Mine has four equally spaced mounting screws with the fuel gauge connector screw in the middle.

Any ideas?

[EDNY]

Not sure if you have it out...but up to 1964 the sending unit worked off the 0-30ohm range and 65 and later went to 0-90ohm range. If still in the tank disconnect the wire to the gauge and check the resistance with an ohm meter. Use the tank for ground, if no reading..establish a good ground on the frame/body and see if it works. If no reading (with gas in the tank)..then you probably have a bad sending unit.

The gauge has 12v with key on, the sending unit supplies the ground in increments.

[EDNY]

Here's a handy tester I made, used a variable 0-100ohm switch. I use it to simulate the tank sending unit..by turning the button I can watch the fuel gauge move up/down through it's range...so I know the gauge is wired properly and working.

Ed

Forgot to mention..you can use another working sending unit as an external tester.

[munch]

Thanks, and my unit does have 5 screws.  I remembered wrong.