96 blazer 4dr LT 4wd--I need to disconnect the fuel lines at the back of the LIM. Does anyone know what size nuts these are?

I can only find a few metric wrenches out of two complete sets (of mine) that my son has used this past year and will need to buy a couple of wrenches to disconnect the fittings (planning on buying stubbys), but I don't want to buy the wrong sizes. The small nut may be a 15mm as that is one of the wrenches I have, but it seems loose on the nut. Any help would be appreciated.