Question about LED's
 

Are there any mods/additions that have to be made/done to install say an LED integrated tail light? Do they require different sending units or any electrical mods?

not really. The flash rate will be affected (blink faster than normal) if you don't do something to adjust that. And the plugs on the cheap one off ebay are slightly different sized from stock, but they still work fine, just either crimp the connectors with a pliers or put new ends on the wires.

You will need a load equalizer or electronic flasher to keep your flash rate the same. Otherwise if you do nothing the flash rate will about double. Some folks don't mind. I use the VFX Flash Equalizer. Seems they don't make them anymore but I'm sure there is someone out there that does.