You may want to consider a "self-leveling" seam sealer for the bed. The self-leveling sealer is applied from a two-part tube thru a mixing tip and flows to a smooth slightly raised area over the seam. Needless to say this is best used on horizontal surfaces but works great for drip rails and other applications where the seams are visible. Unfortunately this is a two-part product and it takes a $40 gun to dispense it but for the serious restoration it can't be beat. Check out Autobodystore.com for details.

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