What should I use to seal cowl to firewall seams?

I have to do a heater core this weekend and was wondering what is the correct seam sealer to use (3M name or part#) to seal the seams. Not for the heater core, but for the constant leak from the cowl area that ruined my carpet last summer?

Paul

 

Check This

thread Should help you out.

 

Thanks Korrie
I'll see if I can get some of that stuff at the local parts store. Does anyone know if the 3M stuff will work in a standard caulking gun?