Elite Engineering USA has them...not sure of they'd give away all the magic numbers though.

 

Tunnel Plate

I made mine 3/8 thk. JMHO, not worth the effort, just bragging right. If you want, I can make a trace for you.

 

I build these also for the c5/c6. I use 6061 t6 and punch the holes 5/16 with the exception of the two alignement holes on the drivers side. I punch those 1/4. I have found that every cars fit is a bit different, thats why GM put such large holes to start with. If you can get them as small as possible it works better, less bolt creep. I use 3/8" for convertibles and 1/4 for coupes. You will notice the difference once it is installed:thumbsup:

 

What does this do?

 

What ive notice the most is the creeking in the roof panel is pretty much gone. It tends to stiffen up the inner frame rails and help with twist when you approach driveways ect.. When I first removed my own plate there was definately obvious that the bolts were creeping around by the marks on the plate. If you ever see one you will understand that the holes are huge compaired to the bolts.

 

Thanks for the explanation, and now I'm very interested.

Can you describe where it's located, or even post a photo?

 

Yes, I will post some pics of the shop car as we installed it as soon as I can.

 

try this it will show yall a little more but you http://s917.photobucket.com/albums/ad19/1c62nv/?action=view&current=DSCN0375.jpggetget the idea. I zinc coat them as well and this is a 3/8 plate while doing a header mod:thumbsup: