They appear to be part numbers if you drop the 'b' and the dots.
The main thing with this procedure is to ensure every rotating piece goes back mating exactly as they were to adjoining pieces, in particular the stub shaft and pinion nut position in relation to the pinion shaft. Also, to replace the stub shaft, the TIS calls for a special tool (of course) to push it back in place. You can't just hammer it in or you'll mess up the pinion preload, so you'll either need to find this tool or be very creative.
The main thing with this procedure is to ensure every rotating piece goes back mating exactly as they were to adjoining pieces, in particular the stub shaft and pinion nut position in relation to the pinion shaft. Also, to replace the stub shaft, the TIS calls for a special tool (of course) to push it back in place. You can't just hammer it in or you'll mess up the pinion preload, so you'll either need to find this tool or be very creative.