This is a type-III bolt housing for magnum caliber rifles. The serial number is very faint and difficult to read, but the style of bolt indicates post-1951 production. The bolt grades at NRA excellent condition with some light wear on the shaft. The handle appears to have been reblued.
We use the NRA Modern Gun Condition Standards Grading System for grading part conditions. You can read about it HERE
NOTE: While model 70 bolts may appear to be interchangeable, to safely replace the bolt in a rifle requires the action to be checked for proper headspacing and lug seating. This is a simple procedure which can be performed in a matter of minutes by a qualified gunsmith.