I believe they're 1/2". I believe that the dimensions they have on the page are wrong. I called them today and they're going to check and give me a call back with the dimensions. I'll post here when they do.
Thanks, from your sig line, we have basically the same build going ...I have a 69, uncut, half cab, building a db 44, 2.5" jbg lift, 1" body, 33x10.50 on factory slots.