When plug welding in a 1 piece floor pan which side should you plug weld from? Do you punch holes in the floor pan and plug weld from in side the car to the trunk, frame rails, and toe board or do you punch holes in the trunk lip, rails, and toe board and plug weld from the under side of the car to the floor pan?

I drilled holes in the floor pan and welded to the supports underneath. I don't know which way would be stronger, but I suspect the way I did it would be plenty strong (haven't had any trouble yet). Besides that it's a lot easier to weld from above, and I've never been too good at or fond of overhead welding.

My opinion is to weld thru the thinner material. If you punch holes in the thicker stuff you run the risk of not getting the proper fill or penetration. I plan to punch holes in the floor for the front, rear, sides and floor brace areas.

You might fill the hole, but not have a good penetrated weld. I will avoid welding on my back at all cost. It's not as safe and gravity will want to take over. My .02 cents.