Trail rig, not rock crawling, keep your 31s and install the 4.56 diffs you got. Switch the aussie locker to the rear diff if possible. I'm assuming the 4.56 diffs don't have lockers, you didn't say. Going to 33s only gains you an inch of trail clearance.
31s are much easier to find replacements on the road and your gas mileage will stay respectable. They are a standard size. Spend the tire $$ on a selectable locker for the front or stretch the budget a bit and get selectable lockers for both front and rear. Selectable lockers will increase tire life and be better on the trail. If you go with selectable lockers you can add them to the 4.56 diffs on the bench then in a weekend install them on the truck.
Another possibility would be to spend some of the tire $$ on underbody armor.
Budbuilt cross members give you a couple inches in the middle at the transfer case cross member without lifting or increasing tire size. What I like about the bud built is it keeps the stock transfer case mount.
If later on you want to increase tire size, adding Marlin Crawler's 4.7 transfer case gears will allow better trail performance despite not having the proper diff gearing.
If you do go with 16" tires, get load range E ones for the extra toughness.
Do you have a winch and recovery gear? That is another alternate place to spend the tire $$$. Read up on winching and recovery before buying. NO HOOKS!!!
There are allot of good threads over at
ih8mud in the
79-95-toyota-truck-tech forum on picking gearing, tires, and lockers for older 4runners and pickups. Unlike pirate4x4 the people are civil.
