I know someone that recently had an arb locker installed by them and they drilled the bottom of the diff for the airline....
That would be me. I'm not sure if that's good or bad, but it leaked oil and they JB welded around the fitting to fix it. It's still weeping a little. It's a shame that these diffs are such a pain and our best installers won't touch them (not that I blame them).
I would trust sixstates far more than gaylons. I had a friend who had Gaylons instal 4.56s in his tacoma elocker. He is not easy on his truck, and I doubt he did a gear break in process, but he blew the rear end, took it back, and blew it again within a year. John @ gaylons is super nice, and he does my driveshaft work. I would trust him to do an 8", but if I were to do it all again, I'd use East Coast Gear Supply.