These Plates

[badasscuda]

'74 Cuda. I'm assuming that they are for stiffening. I have never seen these in any builds or any mention of them in any reference manuals that I have or online.
Just curious as what cars came with these. I've noticed that some cars don't have the mounting nuts in the body. I don't remember what bolts they were fastened with
but a few holes are counter sunk so screws for those. They are 1/8" thick steel. Any info appreciated.

[Katfish]

Might not be factory, never seen those before.
Can't imagine they'd provide any stiffening in that area.

[badasscuda]

I don't know the exact purpose either. But they are factory.

[dougs bs23]

have those same plates in mine and if memory serves me they fasten in with a flathead screw

[badasscuda]

Thanks. Now I know I'm not the only one. What year is your car? Does anyone have pics of the correct hardware?
As heavy as these are, they have got to serve a structural purpose.

[dutch]

pretty sure there`s nothing structural about them.  A few tiny bolts every 4"`s won`t help anything imo   

[anlauto]

1974 only...additional side impact safety 

[Got JOB]

My 74 challenger has them also. Holes in plate are countersunk and plates are attached with flat head screws.

[badasscuda]

1974 only...additional side impact safety 

So structural it is. Evidently the engineers thought it was enough.     Doesn't surprise me '74 only. There are a lot of small changes in the 74's compared to the 70-73 models.
I looked for the hardware and found it. The missing nut plate was the giveaway. Thanks for all the replies. I will wonder no more.

[dutch]

1974 only...additional side impact safety 

LOL...  oh well...I guess they did some testing on that...