I guess diodes are the little black transistors that only allow power to go one way right? im looking or one strong enough to light a set of reverse lights... is there certian voltages and amps these come in? Like for example i found a set on ebay for 6 amp 1000 volt. those would be alright since i would never exceed either 6 amps or 1000 volts right?

to light a set of reverse lights? please explain more on what wires, connections, reason for doing so, not sure if a diode is what your going to need.

i need 12v to go one way and not the other. it needs to be strong enough to light a pair of bulbs

You don't need diodes to light bulbs. Just run straight 12v to the positive terminal on the bulb, and run the negative terminal to the ground.

There is absolutely no reason to need a diode.

if i want power to go one way and not the other i do...
and it needs to be strong enough to resist the power of 2 bulbs a.k.a. 3amps
whats so hard to understand?

I'm curious what exactly you're trying to accomplish.

Yes, a diode will block the current going in one direction, but why would you need this for your lights? The car uses DC voltage and bulbs don't care about polarity. Even LED bulbs don't care, they'll just fail to come on if the polarity is incorrect.

To answer your question, yes, if your load is only 2A, then a 6A diode should be fine.

As mentioned in earlier posts, vehicles use DC current which stands for Direct Current. It will only flow from negative to positive....so there is no need for a diode...unless you are trying to route current through some type of circuit. If you are trying to replace your regular bulbs with light emitting diodes a.k.a. LEDs then you will definitely need more than one diode per light. More likely 20 per light. I think these come in kits. Try googling.