I asked a similar question several weeks ago. After much research I have come to the conclusion a 54 merc gas tank is not being reproduced. I have been told a 54 ford will fit with mods and so will a 56 ford with mods. Both are 17 gal tanks and the merc is 19 gal. I presume your talking about a 2 dr htp. It was suggested I take mine to a radiator shop that repairs tanks. Sure enough I found one that goes over the tank, cleans it, repairs it, and epoxies the inside. All for around $200. Mines is being done now.