Just reading through and noticed your post and thought I'd comment. I haven't had actually had any come out at .018" but I have had one I built for a buddies 11.0 car that came out at .022" and he ran the crap out of it and never had a problem. That's not including the output shaft end play so that adds some clearance. I noticed in Tom Hand's book he recently wrote that Rick Allison at A&A Trans specified .010-.020"
