the drawing number on teh sight base is common on barrels made after 1937, many 37 to 39 barrels had the last number hand stamped,
on a few NM rifles..they switched to a DHT bolt, as the NS bolts felt sticky in a NS action. so they smoothed them out by using a DHT bolt. J5 is a DHT bolt.
the safety sleeve, is a common change, the broke, and wore out easy, for a rifle this old, that likely seen some hard use...first as a NM rifle, then as a spotter, then its seen some hard use.
though uniuqe...its not super rare...but cool. swap the sight out{ easier to do the fix it} and she,s ready for service.
i have seen a lot of NM parts marked with Drawing numbers made after 1937..extractors, triggers, sears, sight bases, sights, buttplates, cocking rods, to name a few..mos fire control parts that were marked as such were also CV marked as well.