80TA

I had broken talilights on my car and have found some at wreckers but even the still sealed ones have lots of dust and dirt inside them.Can I scrape out the old gaskets and use rtv of some type..do they still make the factory gaskets or is that even a gasket?? Can I convert my car to the one piece style..I notice it has less lights or different light hookup than my three piece tailights and lastly what do you guys clean these with..any tips.I hate how they look filled with dirt and dust and water..