Hi, Does anyone know for sure if a 1970-72 el camino frame & a 1970-72 Chevelle wagon frame are the same?

Thanks!!!

not 100% sure but I believe so..

I have always believed they are the same. But, I have no first hand experience at the swap.

The interchange manual says that they will interchange, but I think that the EC frame is boxed and the wagon is not. Since the EC is a station wagon with the top cut off, I think you are safe in doing this. One warning here: these 3rd party manuals have some notable gaps and incorrect info. For example , my manual does not recognize the difference between 2 door and 4 door frames, which are different by 4 inches of wheelbase.
You could do a more extensive search on this site, as you are probably not the first to ask this question. And, if you want to be really correct in this, check with your state motor vehicle department for the rules on this, as the VIN is on each frame.

You will need the transmission mount crossmember to go with the frame. Stationwagon frame not boxed. El Camino crossmember is shorter.