-AN fittings size for trans coolers

[makoshark]

Anyone here familiar with -an fittings. I'm sure they are. Please chime in. On my B&M trans cooler, I can only engage 3 threads of the 1/2" NPT to -6an fitting. That is only hand tight. Will they tighten up more with a wrench and not damage anything? Also, the trans cooler on the radiator is only allowing me to engage 1 thread of the 1/4" to -6an fitting, again only by hand. Will it too tighten up more with a wrench? Or do I need to go to a different size fittings for the trans coolers? The B&M cooler is too large, though, for a 3/8 NPT fitting. Already tried. I don't have an 1/8" npt fitting here to check the cooler on the radiator.

Also, I can't remember, which line on the steering box is the pressure line and the return line? The one closest to the firewall or furthest from it?