A toilet is leaking at a bolt that holds it to the bowl. (See photo.) It is a 1950's Kohler 2 piece with k620 stamped inside the tank. (See photo.) How do I find a suitable tank-to-bowl connector kit? (Searching on Kohler and K620 and connector kit does not work for me.) Should I replace the bolts and washers only or the flapper gasket also? If the flapper gasket also, how do I know which kit to buy.
P.S. The nut on the leaking bolt was loose and I tightened the nut a little more than hand tight. It no longer leaks. But clearly the washer is starting to wear away. So I want to buy the parts to be ready when I need them.