Certer diff VS locked tranny

Is there any way to put a center diff in a savage. Would locking the stock tranny be better? If so how do you lock it? I've been looking for a way to lock it but every time I come across some thing it dosn't look like it will work.
I have the newer savage witch is the 4.6 ss. In side the tranny on the older trannys there is a small ring in front of the one-way bearing. Thats is what you jb weld, but in my tranny there isn't that little ring. Is there any other way to lock it?
Getting back to the diff thing I think I have seen a couple of people who have done it. Each one looks some-what similar. Metalman's looks the best because it is inside the tvps. lots of protection. Where Kap's looks good as well, but there is not much protection for the motor being out side the tvps in all. If someone knows where to get some kind of conversion that would be very much appreciated. Thanks