I have a 88 LX convert 5.0 and I recently replaced the gas tank with a new sending unit and new 255lb fuel pump, I bought all new seals with new locking rings. Before when I would fill the gas tank up it would leak out the top where the fuel pump is located. I made sure that the new o-ring would seat properly before I installed the new tank. When I filled up is was fine no leaks, but when I topped off and filled it completely to the top it leaked out some where the fuel pump is not where the sending unit is. Is it the o-ring not fully settled yet? I would like hear if anyone else has to his problem thanks.