seam sealer options

[ED78CUTLASS]

Anyone know of a good, FLEXIBLE, seam sealer for sealing body joints, especially in the area where the pillar meets the firewall? I have sealed this area in the past multiple times with different sealers and always cracks over time. I am in the process of redoing it again and would welcome any suggestions. It seams what the factory put in there (foam like, rubbery, sealer) is hard to beat. This is for a 78 cutlass.
Thanks,

[88hurstolds]

DON'T use a one part (ie it dries via solvent evaporation) like 3M and others sell...these will come on either a quart can or a SINGLE TUBE. They will shrink up and crack/pull away from the edges.

I heard that 3m heavy body seam sealer in the duramix line works really well. It is a two part sealer and does take a special gun but if you tape off your seams, apply this stuff to them and then wearing a latex glove, wet your finger and start at one end and smooth the stuff out. It looks nice, you have to pull the tape right afterwards or it will be a nightmare to get it off.

[ED78CUTLASS]

Thanks so much. Will check out the 3m sites to get more product info. It is really frustrating when you have to rework stuff since you have to move panels/parts to seal stuff just to have it crack months later and start the rust process.