The Gnutti splined bb/cranks pre-date Williams by over a decade and Shimano et al by many years. Much more precise (finer splines) than Williams too, it's believed that these were costly to manufacture and production never really took off after introduction in 1951/52. Great idea but they simply cost too much at the time.

The crank bolts are an allen key style with alternate threadings (right/driveside, left/non-driveside). The crank arms are 170mm in length, and some examples are fluted on the outside faces, while others do not have flutes.  For use with standard thread (9/16") pedals. The axle is offset towards the drivside, measures 119.5mm in overall length and is stamped "Gnutti Italy Brevete" and "1-OA". The adjustable BB cup is stamped "4/7" and the fixed cup is stamped "5 - 7" and "S".  Crank extractor is a proprietary model and quite rare.  All the Gnutti logos on the cranks are clearly stamped. The back of the driveside arm is stamped "1PA", the non-drive arm is stamped "1LA".