I am replacing a lot of panels on my cuda, including the firewall. I would like to know what are the best/proper-application sealers to put 'between' the panels, (as they are being assembled) and also what to apply over the inside gap once the panels are welded together.

I've seen that the original stuff that oozed out from between panels has a somewhat porous look, like some kind of expanding sealer.

A local supply guy suggests 3m 8505, but I'm not convinced that will meet all the different requirements.

What say you all?

Thanks very much.
Clay