tech on c or z notchin a frame?

I didn't run across a tech post which envolved either procedures. I'm more interessted in Z notching. I want my 38 low and will be runnin air bags in the rear. Any info y'all can give me will really help.

 

there's been a bunch of posts on Z-ing frames in the last two months... it's just that the letter 'z' is kinda hard to search for, huh?

if anyone remembers who posted in them, that'll make it easier to find 'um...