Try Grimes D7315-1. The added hyphen is making your search more complicated; the part number in catalogs does not include it.
The Stock number is: National Stock Number
6220-00-553-8699
Here are some clues to help you along:
"National Stock Number (NSN) 6220-00-553-8699, or NIIN 005538699, (
light,navigational,aircraft) was assigned
January 1, 1963 in the Federal Logistics Information System (FLIS)."
"The manufacturer part numbers were originally supplied by
one supplier."
"This part number has
not been procured by the US Government in
over 5 years."
"This NSN is unique to
one weapons system."
https://www.iso-group.com/NSN/6220-00-553-8699I am late for dinner but I am a bloodhound for such things, and wish I could continue this search. You are looking for a single aircraft type produced for the military in the late 50's to early 60's, that is no longer in use today (or they would have procured more parts in the last 5 years, likely). Good luck and keep us posted. I love a good hunt.