Locktite has their thread lock in a paste form that comes in a tube like chapstick. Because its a paste it will stay on the screws better.

I'm assuming you got the Ofna Spyder diffs? Never had them, they look like stout pieces, but don't look fun to put together. Do they have a grub screw in the diff case to fill from after you put them together like other Ofna diffs? If not I'd stand them up with the screws facing up and put the cap they thread into on last. You could cut a hole in a cardboard box so just the screws rest on the box to keep them from falling out while you fill it.