Luck of the draw.. Your best bet is to buy one and carefuly see which it is. If its the one you dont like switch it for another.

I wouldn't get the yellow RX-7. I'd be 50/50 on the white RX-7 and the Mustangs. I would feel safest with one of the Audis because between my friends, they have 4 Audis and they all have 3-wire setups. Again, we buy from the same RS so it may just be different shipments but that was our experience.

Darn mine has three wires but its different
than all three of yours

If it has all three wires, then you should be able to do the steering pot fix.

Where they're soldered to the PCB shouldn't matter. It's if the third wire is MISSING altogether that you'd be in trouble.

Although, if someone with a two-wire PCB and some experience wants to try it, I bet if you examined the board, you'd find that they've jumpered the two leads right on the printed circuit, instead of using the two wires to do it. If you could find that bridge, and scratch it out, I bet you could then attach the third pot wire.