What would you use to re-seal the gutter along the front edge of the cab-top in a 70 P/U, the one that starts along the doors and goes around the front of the cab.
The best way is to seal it using 3M seam sealer. It is available in quart container. You can brush it on, and wipe it with your finger, or rag to even it out. It fills small seam gaps, and seals out any moisture.
