windshield sealent ?

[panhead59]

It seems that a lot of us have trouble getting windshields not to leak. I will be installing mine soon and don't want to do it twice, or more, because it leaks. After 50 years or so, the lip that is central to it all is rarely "perfect". So is there a sealent or some other "trick" that could aid in this? My 66 GTO uses a 5/16 "ribbon sealent" and a "window weld resealent" for the windshield, made by 3M. Would/could these be appropiate for our 67-72 trucks or are we stuck with trusting a new rubber mounting strip and a prayer? Or maybe just pay a glass shop to do it and make sure they guarantee it not to leak!!!!!