Thanks for the quick reply. My 4runner is stick so it came stock with 4.10's my problem now is just finding a housing. There is one in a boneyard by me, but they want 425. I think thats a little high. I guess ill just keep looking for a housing.
Put your location in your profile so we can see where you are. If you are in the north east or minn/wis area, you probably aren't going to find a non-rusty one locally. I had one shipped up from florida, but that can get expensive too. For just the housing, not the diff and axles, that is an outrageous price. Including diff, it is still high, but probably not terrible (assuming reasonable miles on the diff). Including axles, that is a decent price.
Your other option, which I link to in my build thread, is to patch the rust holes. It is really just the diff cover that is thin, so you can weld on a whole new piece to replace it, or you can just patch the holes by either welding them, or using JB weld for a temporary fix. Of course you still have to find a diff.
Post some pictures of your housing and the holes in it.
BTW, you should do the spin test to double check your ratio. You are probably right that it's 4.10, but you are going to drop some money on this, so be 100% sure of your ratio beforehand. If you haven't counted the teeth or done the spin test, then you aren't 100% sure. Search here for the procedure, it's been covered many times.