I have applied the slop primer sealer onto the undercarriage and also primed the front clip. Common knowledge is that the next step is to apply the seam sealers along the back of the pinch weld and around the seat belt supports before the body colour which will overspray over the undercarriage and of course over some of the sealers.
First added to the title so that the discussion can focus on a single plant and year
Why then, do I continue to see cars with black seam sealer on the floor pans in the area in front of the leaf springs applied after the body color overspray. Is there some reason for this.
First I'm hoping that your looking at unrestored cars and not restored ones.
Not all 69 Dearborn cars had sealant applied along the front rear spring toque box to floor seam and often when it was the last coat of paint over this area would often be the black from the pinch well black out process.
With a car like yours this area often got a coat of sound deadener back in those areas so that would cover any of these details in the long run. Have found examples with body color over the sealer (when applied) along this rear torque box and the rear seat belt inner mounts.m Often there were areas of the surface where the paint was cleaned or wore off since the base material is flexible. Similar to what we find after 50 years in the trunks where the body color no longer is visible/present on the spray seam sealer
The installation of the floor pan plugs was a different station much later using different products