Spindle questions

[xtreme80]

Hey guys I'm planning on buying my spindles tomorrow to get here by next week. I had a couple questions though.

First: With a 3 inch spindle and 15 inch rallies, I have to modify the lower control arm right? What has to be done? I believe it's just cutting the lip off the bottom of em right?

Second: Is it safe to assume that my truck has 1" thick rotors? 80 Scottsdale with a 350, came from the factory with a tow hitch, with 2.73 rear gears. Only the heavy duty stuff had 1.25 inch rotors right? Or should I just go measure myself?

Thanks guys, appreciate it.