Well, I run a True-Trac in the front. Decent LSD and I know it's tight because of the understeer I get when it's active. Honestly though, if you're looking for locker performance you will probably be dissappointed with a LSD. If you're going to spend that much money on a Super35 then I'd really consider upgrading axles, too.
An automatic is a lot smoother then a Manual so there is less shock when shifting gears. The TrueTrac is a LSD and bias's up to 2.5:1 so there is some give. Tractech used to only recommend up to 33's for the TrueTrac's. I've been running mine with 35's for years. But then again, it's in the front which is a bit easier on the axle.