Leaky 350 turbo

[creekwood08]

So i recently bought my 69 camaro it has a 350 turbo. Well the trans leaked a little when i got it. So i decided to change to trans filter and fuild because i had no idea when the last time it had been changed. The new filter came with a rubber gasket. well my dad is one of those old school guys and said put some gasket sealant on the gasket. well i said its rubber does it need it..... wont the sealant keep the rubber from moving when the trans heats up and cools. well i finally just gave up and let him put some on it because he has 30 year more experience than i do. well the trans still leaks. Is it just one those things im gonna have to get over or is there something i can do to help prevent leaking........even if i have to put a new gasket.