i have a fwd laser 91 with no engine or trans. i have a awd 91 talon with trans thats has a bad center diff .

i am wondering if its worth converting to auto to avoid breaking things im about making good buys that last at this point i hear awd break more than fwd or auto break less im just about getting faster right out of the box .
im low on money and need to drive. The talon needs a diff or needs to be welded but i hear that once you weld it you throw out off the streetablity out the window ? and autos do seem to be faster i am wondering how would i build a auto trans like i seen in some you tube vids