If you do not want to work with lead filler (who would want-to if they didn't have to?), there are metal-impregnated fillers that are often a satisfactory substitute.

I can't find the brand that we used 20 years ago on my Suburban's four lead-soldered-joints/locations where the roof is attached to the lower body. We removed the old lead as best as possible, buffed/shined the joints/locations as much as possible, and then applied the aluminum-strands/hair impregnated filler.

The joints/locations have not had any problems after 20 years.

Here is the experience/opinion of someone else who has used this type of product.

EVERCOAT Metal-To-Metal

Alvin Lab Metal - "hairy bondo" looks like anotrher product.
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