I just recently went thru the same thing. I asked here about it a few weeks ago. We had a couple of trailers with horizontal sockets and even more with vertical sockets. So, I switched them all to vertical, which is what I think comes with the Shurco tarp/trap kits. I also use the plugs/sockets as "charge" wire for trailers with 12V batteries mounted on them like our dry & liquid tender trailers.

I ordered the Phillips brand plugs & sockets from "Find-It Parts". Price was OK, service was great. The Phillips plug has off-set contactors so the ground terminal makes contact before the + terminal, thereby eliminating "sparking".

Here's link to Phillips plugs/sockets @ Find-It Parts.

2 conductor vertical plug

2 conductor vertical socket