I.m not sure about mounting my toilet tank I only have one rubber washer, does it go on the inside or the outside?
Thank you
Dave

Hi Dave, is that the large 3" washer you are talking about or a small, black, 1" washer ?

The large washer mounts on the bottom of the tank and will seal connection between tank and bowl.

The small black washer goes on brass tank bolt, then bolt goes through the tank and bowl, than you tighten it up with plastic nut under the bowl ( some manufacturers use metal nut and metal washer instead of plastic wing nut )

However you should have washer for each bolt not only one.

Milo's got this covered. If you have only one washer you are missing some parts. Googling the topic usually gives good results. Try Replacing a Toilet (http://www.lowes.com/lowes/lkn?action=howTo&p=Improve/ReplaceToilet.html#9) This is from the 2nd or 3rd page;
"Install the large rubber gasket over the outlet on the bottom of the tank per the manufacturer's instructions.


Insert the tank mounting bolts and rubber washers from inside the tank, through the mounting area of the bowl.


Place the tank in position and alternately tighten the nuts until the tank is securely fastened to the bowl. Again, do not over-tighten.


Install a toilet seat according to the manufacturer's instructions.


Install the water supply line. If you use the new flexible supply line, this step is easy. If you use a rigid supply line, you will need to do some bending to make it fit. Be careful not to crimp the line—this will obstruct the flow of water and weaken the line, possibly causing it to leak or break."