Be a little cautious about the reference number as well. 80-G or 80-GK types of numbers will work for having someone look it up and scan it in for you, but some of the 19N numbers will not work. Additionally, a lot of shipyard numbered their photos, and these numbers have nothing to do with their current status or availability in the Archives. So a photo from, say, Mare Island Navy Yard that has "123-45" on it is not sporting a number that has any use today; that was an internal number only to the shipyard, and I have yet to find any yard that turned over a list of those photos (none of the US west coast yards did).
80G & 80-GK = good
19N = maybe
anything else = wild goose chase