Door cracking... What to do?

Noticed a crack in my door skin today:



And I've had this crack a while now:



I've always had to slam my doors ever since installing new weatherstripping a couple years ago. That be why?

What's the best fix? Weld it up? Ignore it since my doors aren't all that great anyway?

In this post Dave said:

FuzzFace2 wrote

The other thing is the brace between the outer door skin and the inner frame to support the mirror.
With out the brace the door skin will crack and it would need to be removed for that glass.
Dave ----

And in this post he said:

FuzzFace2 wrote

What mirrors dose the truck sport?

There is a metal tap? that runs from the inner panel to the outer door skin.
This tab is by the vent window down post IIRC
This tab supports the outer door skin because of the heavy mirrors.
With out this tab the outer skin will flex and crack.
It could be this tab is broken but has not cracked the skin yet and when you hit bumps it is flexing and making noise.

Also the vent window post has a bolt to then inner panel to support it.
If this bolt is loose or the tab on the post broke loose this could be making noise.
Also check this bolt washer that it has not cut the panel where it is bolted to.
Dave ----

So do you have the tab or brace?

I'll have to check later. Sure enough, lightly tugging on the mirror flexes the door panel right there.

Took a look. The tabs are still there but cracking on both sides:





And more on the back of door cracking:



Noticed the front of door exterior cracking on the passenger side too:



Guess that's what I get for slamming doors. But if don't slam, the door doesn't latch. Seems that door seal (LMC) didn't break in soon enough. Or just old damage from nearly 40 years of service?

What's the best fix? A lot of welding? Fresh doors? Or let it be for now until it gets worse. Gee, and I thought my leaking cowl seam was the worst of my body issues (and rotten vsb corners and a rotten bed side). Ugh. These things are demoralizing, especially since it's likely to get worse.

The tabs may be there but are they still welded to the inner & outer panels?
On mine the tab broke loose on 1 side of the panel.
I welded it back in place and welded the cracks and have been good for 4 years now.
Yes I have to slam the doors as I installed new seals.

If the tab is still welded  then you need to look where the tabs stop and where the cracks are.
My guess if the tab is welded that the cracks are on either side of the tab.
I dont know what I would do in that case?
Dave ----

The tabs are cracked but still welded to the panels (and to eachother). Not fully disconnected... but failing.