I found a frame that the guy tells me is from a 1969 Chevelle convertible., can someone give me a way to make sure thats what i am getting, and that its not a el Camino frame or wagon or even one from a coupe ?
Any help would be appriaciated. Thanks -

A convertible frame is boxed/enclosed in the mid section. A coupe is not. An Elky frame is also boxed but about 4" longer that a convert.
A wagon frame is the same length as an Elky but not boxed.

It should still work on a coupe body, might be heavier, though.

El Camino and Convertible are boxed, all others are open.

El Camino will be 10-1/4" longer. 4" in the wheelbase (112" vs 116") and 6-1/4" longer in the rear. Also, at the rear body mounts, the frame curves up 1" higher on a coupe/sedan/convertable frame, and is flat on wagon/el camino.

"IF" it hasn't been cleaned up you may also be able to tell if the "extra" body mounts at the firewall were used........

ok, i know that the convertible frame is boxed., but walking up to one on the ground that is already stripped how would i know what it is ? What extra mounting points ? Something that is easily identifiable or something that i can measure and be sure that i am buying one for a Convertible and an El Camino. Thanks-

Print this out, and take a tape-measure.
http://www.chevelles.com/showroom/framedims.jpg

Derek, thanks alot, thats exactly what i needed.
Many thanks -