1963 Belvedere Lightweight?

[old5.0]

I've never heard of any such animal, but that doesn't mean it doesn't exist. There was a high-perf inline dual four barrel 413 available very early in the 62 model year, but I believe it was canceled when the Max was released, and survivors are few and far between. I'm not aware of a similar option for 63. I think that B-Body options that year skipped right from a 383 to the Max Wedge.

It could be something that was built by an individual very early on. As an example, I've heard a story that the parts manager at Feld Chevrolet in Kansas City, KS built his own Z-11 Impala with service parts on a brand new 409-425 Impala hardtop. Even though that car was not built as a Z-11, it had all the special parts on it almost from day one. This car could be similar.