Welcome to this forum, and I would go ahead and put the 33" tires on the axles you already have. I have friends that run 35" tires on their stock axles, with lockers on both ends. Especially if you are not doing a lot of rock crawling. If your D-35 ever gives out on you, then go ahead and upgrade it. I wouldn't throw it away until then. The aussie lockers will work just fine, and the gears are a good choice.