First off I did use a search or two.

I want to experiment with using LED's in my tail light I found a source for leds:
SOURCE HERE

With this what type of resistors would I need? I also want to use a few of them singly- by that I mean I want to find a resistor that I can solder to it and have a + and - wire much like the Hyper Leds you see on ebay for $10. And one last question how bright are these?

 

According to the listed specs, they are not very bright at all. 2mcd @ 10mA and 5mcd @20 mA is squat for brightness. They are not bright due to the wide dispersion angle (60&deg.
Ideally, you would want at least 6000 mcd, and preferrably more, with a dispersion angle of 10° or so.
I located a seller on ebay a while ago who is offering 12,000mcd LED's at 50 for $12; he has none listed as I type this, but here is a recent listing
http://cgi.ebay.com/ws/eBayISAPI.dll...ory=26207&rd=1
About resistors - here is a page where you can plug in a few values and get the proper value of resistor needed http://linear1.org/ckts/led.php . If you are using the car's voltage, use about 14.5 volts in that calculator to account for the charging voltage. If you are using a regulator (12V for instance) use that voltage. The plus of using a regulator, is the LED's won't dim down when the charging voltage drops at idle or high loads.
For the LED's listed in the auction link @ 14.5 volts, you would need a resistor with a value of 628 ohms or the next size higher; a 1/8 watt rating would be sufficient for a single LED.
Hope this answered a few questions for you..

Pete

 

Thanks for your reply. You answered all my questions.

 

Go to your nearest auto store, one that is up to date like Autozone or Advanced Auto. THey make OEM style replacment bulbs now. They cost a bit more, but say for my truck, I can replace all of my signal lights for about $80. It may sound like a lot, but at the same time, you'd never have to replace those lights ever agian.