Mike Butters makes reproduction Gas Caps for the 29 Durant, with the "D" molded in the top.
You can find their address etc in the "Reproduction Parts" ads in the back of the Durant Partner.
They do good work.
Where Are You From? Guelph, Ontario, Canada
Do You own a car built by Durant? 1932 Frontenac built by Dominion Motors Ltd. Leaside