Exhaust smell in cab

My 65 was the same way when i got it. 2 probloms I found were trunk seal & the centrr trim between the tail lites (GT model's) was installed upside down. That caused the tail lite assemblies to have a 3/8 gap between the body and the tail lamp bucket. Adjusted trunk lid & installed center trim correctly & problom was solved! Any gaps along the trunk or above tail pipe will get sucked in the cab when driving down the road.