looks like i have leak coming from where one of the brass fittings goes into the bottom of the gas tank. is there a brass insert pressed into the tank for the fitting to screw into? what is the best thing to put on the threads of the fitting to hopefully stop the leak? teflon tape? or something else?

 

WHAT YEAR AND MODEL! Some early tanks have screw in fittings,while later ones have grommets with inserts! If have screw in fitting,teflon tape should help.