Seam sealer.

[Wayner]

A question for you body guys. I'm replacing the rear fenders on my 76 step-side. Should I use seam sealer between the fender and the bed? I noticed some rust on the bedsides at the mounting holes that I have to repair and I would like to prevent this in the future.

[Ed4all10]

I think if you get rid of the rust and paint it right, you should be fine if you wanted to seal it. Granted, the only seam sealer I have used is on marine applications. I use 3M brand because it takes paint well. A word of caution, though. I have found in my applications that some seam sealers are solvent based, and do not last long. Make sure you find one that isn’t solvent based, and they last much longer. I have some 3M sealer around the wheelhouse of my boat, that I put there several years ago that has held up nicely. When I renovated the boat I wire wheeled the rust, and applied 2 coats of primer and pant before sealing it...good luck!

[Henry]

Hi Wayner:
I believe that the metal beds all had seam sealer from the factory in the joint between the bed and 3 sides. You can buy a good quality seam sealer from auto paint supply stores...in addition to 3M, SEM is a good brand with 3 different colors. On my 76 fleetside long bed, it took exactly one tube to run a bead around the entire joint. So if you have a short bed, one tube may be enough to get the joint as well as the bolts.
Regards,
Henry

[ehjorten]

The factory didn't use a seam sealer on the stepside fenders.  They used a type of caulk to prevent squeaking between the metal.  Look for 3M Strip Caulk.  You can find fender weltings available too, but from what I have heard others say, it doesn't look good and often starts to walk out of the joint in places.