I believe that was actually an aftermarket kit, not a factory thing.
After all, that supercharger doesn't look like anything GM would be using. GM would have a snout specifically cast for the application. That one is the one they use on their aftermarket */Cs. It can be cut and machined for whatever specific length the customer needs. The ones they produce for factory applications have one-piece cast snouts with ribbing along the shaft, like ours.