Not all 2 prong radios are the same, Nick, so you've got to look into what you're buying.
There are several different kinds of proprietary radio connections that are 2 pin connectors. I'm not sure of all of them, but the differences lie in the different manufacturers; Motorola, Kenwood, etc.
I'm also not sure if any are cross compatible, but that may be the case sometimes. I know some of the radio accessories that I tried in the store would fit, but they didn't work. Sometimes the plugs will fit, but you'll notice that its acting like its constantly transmitting.
If you need a radio with 2 prongs, I'm assuming you already have some accessories for it, so you'll need to make sure to purchase a compatible radio.
I think that the black line arrangement on the pins has something to do with the format of connector it is, but I'm not entirely sure on that.
The best way to do this would be to just take the stuff with you and try it out in the store.
Hope this helps a bit.