I have been looking for a 6 volt negative ground fuel gauge for quite a while and have finally found a source.

Steinertractor.com has a sender that works with either 6 or 12 volts (14 to 122 ohms) Part # FDS199.
4WD.com has a 6 volt negative ground gas gauge (Omix-ADA 17210.06)

I have yet to install this in my 1926 Star but did a bench test and it performed as expected.
This may be of interest to some of you.

Where Are You From? Kamloops BC Canada

Do You own a car built by Durant? 1926 Star Delivery Van

Ken, Thanks for the help I've been looking for that same gas gauge. Ordered one thru Summit Racing for my 27 Star.. Dave Coppess

Where Are You From? Custer, S.Dakota

Do You own a car built by Durant? yes, 1927 Star