While thumbing through some literature about '68 Camaros I got from Chevrolet's Customer Assistance Center several years back I saw the following about the body structure:

"Deeply ribbed and contoured floor panel with underbody reinforcing crossmembers."

Back in April I asked for what and where I should look to see if my floorpans had been properly replaced. Besides the braces that the seats mount to in the passenger compartment, what other reinforcing crossmembers are there (in other words, where are the "underbody reinforcing crossmembers")?

Thanks.

A coupe doesnt have the underbody braces like a convertible(at least in all the camaros Ive cut up and junked). All it has are the seat braces, and all have the ribs in the floors for strength.

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67 Camaro SS Conv.
70 Challenger R/T Conv.

Ditto on that. The reason the convertible has the cross braces and the coupe does not is that GM felt like they needed to give the convertible somer additional chassis rigidity to compensate for the fact that some was lost due to the absence of a solid roof panel.

As a side note, It would be a mistake to put an extemely torquey motor in a convertible. Over a period of time, stress cracks would develop due to chassis flex even with the cross members in place. That for instance is exactly why the new Corvette Z06 385HP LS6 option is NOT available on anything but hard top coupes.

'67-'69 Z/28 was not available in convertable either.

Both Global West and Art Rasmussen recommended solid body mounts and welded subframe connectors to avoid the stress cracks. These mods go a long way toward making for a stiff platform. Of course, a 502 would let me speak from experience!