Untill you've tried to save your old tank and failed , never wa$te your time and $ on re-pop tanks as they ALL suck and about 2/3 of them LEAK too ! . not good .
It's a rare tank that cannot be saced by carefull cleaning and relining .
Look in the 'phone book under Gas Tank Re NU , it's a natio wide chain that specializes in this typ of repair .
The re-pop tank should have fit right in the alotted space with no mods and began leaking as soon as you filled it up .
Maybe they sent you the wrong tank ? just a thunk .