I wrote that article on the Inliners site and yes, the spring clip is needed to locate the gear - the dimple had to be drilled by a machine shop. No way a normal drill can touch that hardened surface.
The Astro Van T5 shifter has about the same geometry as the $170 Hurst shifter from Summit. Of course I didn't discover this until I had already sprung for the Hurst :mad: .