The Frank Stella BMW 3.5 CSL "Art Car" competed in the 1976 24 Hours.

BMW Art Car #41

It appears that it does not bear many, if any, of the regulation markings (for class, etc.), as can be seen on this companion BMW.

BMW #42

I've been considering converting one of these (actually have it for sale on eBay, but I don't think anyone is going to offer me what I feel it is worth) from the #21 to the #41, which should be pretty easy, but wanted to make it as accurate as possible.

Other photographic results to the contrary, am I lead to believe that the ACO allowed them to race without the required identifications, thereby making my conversion overly simple?