Well I've been looking at the gears from Kamdiffs.
They offer 4.75, 4.1 and 3.8:1
http://www.kamdiffs.com/ratios_detailed.htm
According to them the 4.75 gears should be pretty strong, I know a few people who have broken ring/pinion teeth. They also offer upgraded driveshafts, although I don't think I'd worry until I actually broke one.
I run 33.11.50 R15 at present. This is up from stock 28" tyres for 1991 models. These tyres really kill on road accelaration and I'd like something that is capable of going slower in low 1st when off roading. Also the extra umphf offer by the lower gears should be a benifit.
Do you think 4.75 is over kill and I'd be better off with 4.1:1 gears instead. I just don't want the engine bogging on steep inclines while off roading. The diesel makes great low end torque, but only once the turbo's kicked in.