Frame Rail?

[gtomike1966]

Hi,
I have been looking to buy a 67 to 69 Camaro. I have seen alot of ads stating the cars frame rails are good or the cars frame rails need work/replaced. I have owned GTO's in the past so this frame rail thing is new to me.

Can somebody give me a quick lesson in frame rails and what to look out for in a car? I understand that Camaros are Unibodys? And they have a front detachable frame (forgot what you call it) but I thought the rest of the body was all one piece except for the obvious doors and trunk lid.

Thanks!