I have an up close pic and a wide angle view.
On the under side, the crack is very close to where the stamped sheet metal that makes up the "frame" that the trans cross member bolts to comes to an end.

The only thing that I can think of that might have cause it was when I bought the car the rubber portion of the transmission mount was gone when. It would bang as it shifted through the gears.
But that was 13 years ago and its not rusty around the crack. The only rust that I do have is physical damage from some moron sliding over rocks with the body.

I can weld the crack very easily, there is no thin rusted metal around it.

 

I've got a 1988 white IROC with a similar tear in the transmission tunnel sheet metal.

Just assumed it was some kind or accident damage and never worried about it.

 

I have had the car since 2002 and pretty sure it hasn't been crashed before I got it.
The crack doesn't look like its been there for 13 years.

 

Ditto here. I have one that had been crashed and had the same crack in the same spot. T top car. Is there one below the shifter bracket?

 

I found a few more smaller ones too and welded them up too.
All the cracks welded up real easy (no thin rusty metal).
Other smaller ones I would say were under the shifter bracket, didn't have to remove the shifter bracket to get them, there was plenty of room to get my angle die grinder and mig gun in there.

I am wondering if the air force pilot that had the car before me took it off road unexpectedly, cause its been over some rocks and I didn't do it.

The car has been in for an alignment and they just had to move the strut towers and turn the tie rod connector. Before I bought it I took it to a mechanic with good rep to check out if it had been wrecked.

I guess I should just run the vin, (wasn't as easy to do in 2002 as it is now).

Lets assume a pilot thought this Z28 was a T38 and maybe caught some air or put it in a ditch with out trashing it. What else should I do or look for?

 

I wouldn't think sheet metal tears like that from any kind of impact because there's no evidence of bending (like a soup can).

I think it's more of a fatigue issue.

 

My car is a C & C T-Top car and fatigue is a likely cause of the crack in the transmission tunnel.

Recently I install BMR sub frame connectors, which I hope will fix any weakness.

 

Sounds like a pretty good case in favor of getting sub frame connectors.
I have a 454 that will put out about 3x the torque of the 5L to put in the car, its developed cracks with normal driving with a boring engine yeah I think I should get some sub frame connectors.

 

More pics.

There was one more I found one more directly above the original drivers side crack, it was a hair line. Given enough time the 2 cracks may have merged.
Then when I knew there might be more, I found them on the passenger side.

I am not used to welding metal so thin. I used Lincoln 0.025'' L-56 wire and CO2. I should have brought out the argon/CO2 mixing rig but I was running out of day light and rain was moving in.

 

Mo crack.
I cropped the picture down so it would be as clear as possible where the crack is in relation to a good, known reference point.
Here its straight below the hood popper.

 

That's a lot of cracks ! How many miles your car has ? Is it raced ?

 

Its got T-tops and around some where between 180,000 and 200,000 miles.
I replaced the speedo with a 145mph unit a few years ago and don't remember exactly what the mileage was.
As far as I know it was not raced.

 

Wow bust out the welder and also put in some subframe connectors

 

Any cracks that weren't welded in the picture are all welded now.
Its getting SFCs just need to pick out the right design.
I am going to build them my self.