There are only two stock configurations of pinion shafts, splined 4th with a clip and keyed 4th with a nut.
The early pinions with keyed 4th were only used with early 4 bolt pinion retainers. When I started this topic, it was meant to record only the shims used with late threaded pinion bearings. All of those used late pinion shafts with splined 4ths.