'29 cabriolet body parts

[wingski]

Another question. A guy who also owns a ’29 cabriolet told me that to get replacement body parts on my ’29, I’ll have to order ’32 parts. Is this possible? I know that my ’29 cabriolet body is bigger than a roadster, both in length and width and definitely heavier, but what causes the difference? If this is true, is it due to the fact that the body was manufactured by Briggs?