235/75's are within about a half inch of 30/9.5's. most tires in those sizes run about 29-29.5 inches tall. the 3.73's would work, but with your 5 speed tranny, your engine will be happier with the 4.10's so you can use your 5th gear more on the highway. pulling away from stops in city driving should also be easier as you'll be accelerating to traffic speed quicker, and using higher gears in the 30-50 mph range. you may find yourself in 4th gear at 45 and lower rpms with 4.10's where before you might still be in 3rd and higher rpms at 45 with the 3.45's. all i'm saying is you will notice a pretty big difference in overall performance and hopefully mileage.
as for lockers, the LockRight is good and works, it is just noisy and you get the big "snap" every now and then when it unloads. the Detroit is noiseless, very strong, and the ultimate in reliability, imho. the selectable's are nice, but very spendy. and with all those extra parts needed to engage and disengage them, there are obviously more opportunities for problems. yes, the ARB's and Ected's can and do break occasionally. we've all seen it. i'll stick with my Detroit and be a very happy camper.
good luck.