Definitely different. http://www.ebay.com/itm/1981-Buick-Skylark-/302370724060?_trksid=p2141725.m3641.l6368
Poor decision to have it aftermarket rag-topped. T-topping it would have been much preferable. At $338 current bid, it's still worth trying.
I would think those cars would be a structural nightmare. They weren't that stiff to begin with, and to lop off half the body structure, well....
It depends on how competent they are at reinforcing the remaining structure. Back in the early days, it was easy enough to drop a convertible body onto an X-frame.
The question would be, "Did the company X-brace the body and weld in the strengthening members before lopping off the top?"
You would need to do at least two things to this one to make it acceptable. 1. Major reinforcement in the inner rocker panel area, basically installing a large frame member from the front wheel opening to the rear wheel opening. 2. Reinforcement from the front strut towers to the firewall.
And the rear strut towers to rear seatback panel and the rear strut towers to each other and...... I had a '81 Skylark when they were new. Not what I would call a "stiff" car...