Vintage Shimano part - part number is unknown 

I think it is for one of the following hubs: FH-R050 - FH-T300 - FH-R080 - FH-IM70 - I'm not sure of interchangeability between these. Please check the dimensions listed below against the one you have. 

Freehub is 7 Speed length rather than 8/9/10.

Dimensions are:

Overall Length: 75.3mm

Measured Thread Diameter: 23.83mm

Thread Length: 15.64mm

Diameter Of Part That Sits Inside the Hubshell: 34.08mm